Smartphone Performance Explained - All You Need To Know !

What do you consider when buying a new Smartphone ?

Well, the most common answer to this is, "Oh ! I look for a ton of things including the Design, Display, Camera, No of Cores of the CPU, the amount of RAM, the amount of Internal Storage & the Brand the device is coming from" .  Ok so sure, these or I may say most of these are actual things to look for but, when it comes to day to day usage, the overall Performance matters the most.

In this article, let me tell you about the essentials that'll determine the Performance of your smartphone & I hope this article will help you a lot in terms of raw knowledge so you can make the right purchase decision from the next time and be sure that you're not crying on your purchase after using it for a couple of days.

Quick Note: This article is only focused on the Raw Performance of a smartphone & other things are not included here. To know about Smartphone Displays refer to my article on that by clicking here. Explanations on other important essentials are coming soon to keep sure to frequently check back the Fan Share section for that.

So, first I want to make a point clear. Each & every user have different kind of of needs when it comes to Performance. While some people need bang on power for playing High End Games on the highest settings available. Some need a medium processing power for Good Multitasking with a Decent Gaming experience. Also, there are people don't even care about these kind of stuff & just want a phone that can handle their day to day tasks like Web Browsing, Document reading & apps like Facebook, Whatsapp etc. without any problem.

We'll need some kind of tags to define these segments of people. While we cannot address every kind of user here, we can address the three main types that I just mentioned above.  Starting from the end, let's address these segments as "Normal User", "Mid-end User" & "Pro User" . We'll come back to this discussion later but, first let's talk about the aspects of Raw Performance.

When it comes to Performance, there are five main components that decide it's characteristics in a perticular device. These  componants are SOC (CPU), GPU, RAM, ROM (Internal Storage) & last but not the least, the Software.

So, whats the big deal here ? I'll just pick up an Octa-core Prcessor with as much RAM & Internal Memory as I can fit in my budget & that'll hold up just fine right ?

Well that may sound cool but actually, it's not the reality at all. There can be a lot of things going in there. So, first get out of the numbers game. It's not that numbers mean nothing but trust me, they're not that much important most of the time. So, let's break the details down for those five main components one by one.

So, first is CPU. Now, this is the part where all the logical instructions are executed. So, all the instructions that need to be executed for your device to perform specific tasks are processed in this part. Anyway, now-a-days Smartphone CPU's include a lot of other system units along with the main processing unit & that's why they're called System On a Chip (SOC). So, you have a lot going inside the same chip that'll determine a lot of qualities of your smartphone. So choosing the right CPU (Processor) is important.

The main properties that determine a CPU's performance are, Cores, Clock Speed(s) & Process Technology. Depending on how well these properties are implemented, the performance of the CPU will be effected. We will focus on these properties one by one here.

Now, the one misconception that many people have is "An Octa-core processor is always better than a Quad-core processor". This is not the reality at all. Smartphone SOC's don't work that way. There are two types of cores that can be present in a Smartphone CPU. These, are known as Big or High-power cores & Small or Low-power cores. For example,  Cortex A73 is a High-power core & Cortex A53 is a Low-power core. Let's look a the below image carefully,

So as you can see in this image, a Smartphone CPU can have core configurations like shown. We do have only Quadcore & Octacore configurations here but, for other configurations like Hexacore & Decacore, they work the exact same way.  So, you can get a CPU equipped with either HP Cores or LP Cores or Both.

Now as the names suggest, High Power cores deliver more performance compared to Low Power cores but, they'll also consume more power. In the other hand, Low Power cores deliver less performance but, they comsume less power.

Clock Speed & Process Technology will also effect these things so, we're coming to them next.

Clock Speeds are basically the Frequency that the Cores are running at. In a perticular configuration, Higher clock speeds will lead to faster performance. But, there is also a flip side of the coin. Though the performance increases, higher clock speeds may also lead to more heat output. Now, that'll also depend on the Process Technology that we'll come to a bit later. Generally, CPU clock speeds are calculated in Gigahertz (GHz).

However, if a CPU has a combination of High (HP) & Low(LP) power cores, the HP cores are always clocked Higher & the LP cores are always clocked Lower. This HP-LP section mainly includes CPU's with two different core configurations (Example: Snapdragon 653 that includes 4 x 1.95GHz Cortex A72 + 4 x 1.44GHz Cortex A53) .

But, this clock speed property HP-LP combination for a single type core configuration are also available (Example: Snapdragon 835 that includes 4 x 2.45GHz Kryo 280 + 4 x 1.85GHz Kryo 280). In this case instead of calling the lower clocked ones LP cores, calling them Energy Efficiency cores seems to be more practical. But, in the end the purpose is exactly the same.

Now, not everytime Higher clock sppeds produce more heat. Seems like the opposite of what I previously said ? Well, you need to understand the purpose of Process Technology to make it clear. So next, let's jump to that.

Now, when you guys hear something like "This is a 14nm Processor", many of you kinda think that, the measurement in Nanometers refers to the Size of the processor. Well, let me tell you that's not the truth. 14 Nanometers is so small that an object having that size cannot be even seen with naked eyes.

So, what does the value in Nanometers refer to ? Well, it's the distance between two parallel Transistors on that Processor (Refer to the image above). So, as a reference of this, we use the term Process Technology & state it as the measurement of that distance. Process Technology is evolving really fast & that's why we now have 10nm processors & 7nm processors are in development stages. So, as you can probably guess by now, the smaller the size of Process Technology, the better the overall performance ratio.

But, what is the purpose of reducing the Transistor distances (a.k.a. Process Size) ? Well, it may sound complicated but, it's actually damn simple. When you reduce the distance, the current needs to travel less path. That means the Overall power consumption is reduced & less heat is generated. Also, less travel path translates into faster performance of the processor. So,  with a lower Process Size, CPU's are faster & way more energy efficient. For example, in a similar core configuration, a 14nm Processor should consume way less energy than a 28nm Processor and also, produce less heat while giving more performance. So, I know that some of you guys will be confused with the above info but in parctical aspect, I got pretty similar results while testing different devices throughout these years.

So, what the hell is a GPU that everyone seems to be hyped about ? Well just like CPU, a GPU is another processing unit but, this time it deals with the all the graphics that show up on the top of your screen. GPUs normally have a lot more processing units compared to CPU. These units execute identical calculations together parallely to render out the graphical data. We do have some really powerful smartphone GPUs out right now like the Adreno 530 & 540 from Qualcomm, the Mali G71 MP20 from ARM.

Just like CPUs, we do have clock speeds for GPUs. Till now we only see smartphone GPU clock speeds upto MHz but, maybe wait for few more months or an year & I'm pretty sure we'll have smartphone GPUs housing GHz clock speeds. But, along with the Clock Speed there is another unit that we use to determine the Processing power of the GPU known as GFLOPS (Gigaflops). FLOPS stand for Floating Point Operations Per Second so, GFLOPS stand for Giga Floating Point Operations Per Second.

In theory if your GPU has a good combination of Clock Speed & Gigaflop power, it's a good GPU. Taking Adreno GPUs for example, Adreno 505 (450 MHz & 48.6 Gigaflops) is a Low-performance, Adreno 506 (650 MHz & 130 Gigaflops) is a Mid-performance & Adreno 540 (710 MHz & 567 Gigaflops) is a High-performance GPU.

Now, in case the difference in Gigaflops is not that much, a GPU with slightly lower Gigaflop count & a higher clock speed may outperform a GPU with slightly higher Gigaflop count & a lower clock speed. For example, during my testing periods, I have seen a Mali-T860 MP2 (520 MHz & 35.3 Gigaflops) outperforming an Adreno 505 (450 MHz, 48.6 Gigaflops).

Now, let's talk about Random Access Memory (RAM) a bit. Well, in easy words it's the Middleman between your CPU & the Storage of your device. Basically, your CPU needs to fetch processing data from your OS to perform the mandatory tasks. Now, OS is stored in your local (internal) storage that is fast but, can't match up with the transfer speed of the CPU. This is where RAM comes in. RAM is way faster than your regular Internal Storage & it actually stores some parts of the data & supplies that data to the CPU whenever it is needed.

Now, you may have noticed that we don't use the term DDR (Double Data Rate) directly to specify a RAM type. We actually use LPDDR (Low Power Double Data Rate) instead. Basicaly LPDDR is a low powerd version of the DDR that is Way more power efficient & as you'll expect, Less powerful compared to their Desktop family.

Now, it's 2017 & smartphone RAMs have came a long way. Don't worry about LPDDR1 RAM as you'll never find that in any smartphone. Even LPDDR2 RAMs are rare at this point. Some older low-end SOCs like the Snapdragon 400 & 410 do support them but, manufacturers almost never use it & end up using a low-frequency LPDDR3 RAM instead.  

LPDDR3 is the type that'll you find in almost all low, mid & higher-mid end smartphones these days. Mordern SOCs include LPDDR3 support from 800 MHz all upto 933 MHz frequency & those are great performers. But, for High-end premium devices we have LPDDR4. Mordern High-end SOCs hav DDR4 frequency support upto 1866 MHz. Though, we have started to get LPDDR4 support in Mid-end SOCs as well (Snapdragon 630 supports LPDDR4 RAM at 1333 MHz).

So, talking of SOCs you'll find LPDDR3 RAM included systems with SOCs like Snapdragon 430, 450, 625, 652 etc. LPDDR4 RAM can be found with systems eqipped with Snapdragon 630, 660, 820, 821, 835 etc. But, even if you buy one of these SOC equipped devices, you may want to check the Official website to make sure if the Device Manufacturer company have included LPDDR4 because some of these may be backward compatible with LPDDR3.

Now, the most 2017 thing in Smartphone RAMs, is a upgraded standered known as LPDDR4X. As of now, this technology is still mostly in development stages & Snapdragon 835 is the only SOC that supports it. At the current stage, LPDDR4X bring some minor improvements over the normal LPDDR4. The most important improvement is Reduced Power Consumtion & beyond that it's currently almost identical to it's predessessor. Snapdragon 835 also supports LPDDR4X at a similar frequency of 1866 MHz just like a high-end LPDD4 RAM. But, I am confident that this technology will evolve in future & we'll also get much higher frequencies with LPDDR4X.

Now, this is the part you guys are actually interested in. Probably the most asked question about smartphone RAM is,

"How much RAM do we actually need ?"

Quick Note: In 2017 there are very few phones out there with 2GB RAM & frankly you should not go for any device that has less than 2GB RAM. So, when you're really stuck on a very low budget, I recommend to look for at least 2GB of RAM. To understand this RAM capacity game further continue to the rest of the article.

Back to the actual topic now, how much RAM your device needs, mostly depends on two factors. Number one is what you do with your device & Number two is what SOC your device is rocking.

Clarification For Number One: If the user is just doing regular stuff with their device like Web Browsing, Chatting, Watching Youtube Videos, Streaming Music Online etc. 2-3 GB RAM shall be enough. If the user is doing heavier tasks like Swicthing between Apps frequently while keeping the other apps active in the background, Playing High-end Games, Doing casual VR stuff etc. 3-4 GB RAM shall be enough. Doing something like more insensive like Editing 4K Videos on your Smartphone or working with 3D stuff will require 4-6 GB RAM.

Clarification For Number Two: Equiping  a Smartphone with High Capacity RAM is not always enough to make the device perform extremely well. If the manufacturar includes a High capacity RAM in a device that has a Low-end SOC, it can be a bottle-necking factor in that device. Basically what this means is, the device won't be able to take advantage of the full capacity of the RAM. The opposite is also true. If the manufacturar includes a Low capacity RAM in a device that has a High-end SOC, it can also a bottle-necking factor in that device.

For example, if a device has a processor less or similarly powerful like a Snapdradon 425 or 430, it shall not require more than 3GB RAM. Having more than that will probably not get used for actual performance purposes anyway. In the opposite side, if you similarly use 3GB RAM in a device that rocks something similar like a Snapdragon 821 or 835, in actual need cases, the lower capapcity RAM may limit it's actual performance. So, minimum 4GB RAM is recommended here. Including 6GB RAM is a plus but, it may not encounter real life use cases very often.

Now, I know what do you guys are planning to fire on me here. Ok, I am aware of the fact that, Zenfone AR has 8GB RAM & the need of 8GB RAM is not included anywhere above. But, this is a device that may actually need that RAM in real life use scenarios. As you may know that it comes with inbuilt support for Google Tango AR Platform. So, it has a lot to do with 3D. In case it's rendering a captured area with tons of details. This is where it needs that extra RAM. You may already be aware how much RAM is needed in these Graphics Rending related works. And the being a High-end SOC the Snapdragon 821 can take full adavantage of that RAM. I hope this omits all of your doubts.

Let's talk about Storage (a.k.a. ROM) now. I think we all are concerned about the amount of Internal Storage that our phone has. Well, this is a section that doesn't need a lot of explaining as you want to grab as much storage as you can get in your budget keeping the above sections in mind. But, as you would expect there are different kinds of Storage options available for Smartphones. So, I'll discuss this a bit anyway. So, have a look at the image below,

The most frequent type of storage that you'll find in most of the Smartphones out there is eMMC (embedded Multi Media Card). These are quite fast & in practical scenarios the latest eMMC 5.1 give Read speeds around 200-300 MBPS & Write speeds will stay close to 100 MBPS or less. However older eMMC versions will definitely give lower speeds as well. The eMMC cards are okay for regular & even mid end users. The main downside of eMMC is the lower IOPS (Inputs & Outputs Per Second / Input-Output Operations Per Second) rates. We use IOPS to determine how good the storage can handle small random operations like Database tasks for example. This makes eMMC a bottle-necking factor for many of the High-end SOCs out right now. So, this is where UFS comes in.

UFS or Universal Flash Storage is way faster compared to eMMC. The UFS storage options that can be used in Flagship smartphones include UFS 2.0 & 2.1 . UFS 2.0 is a huge step up over eMMC with around 500-600 MBPS Read & 150-180 MBPS Write speeds. UFS 2.1 is even better with around 600-800 MBPS Read & 170-200+ MBPS Write speeds.


These are not any specs sheet speeds, these are practical case scenarios. IOPS is also a huge advantage here with almost 10 times of IOPS scores over the regular eMMC. This makes UFS perfect for High-end SOCs to use their capacities at the maximum level.

Though, Hardware is a real game changer for Smartphones Performance, Software is also important. I don't want to dig too much into Software in this article but, I'll give you a short but, clear idea that how software can effect the performance of your device.

So, we have two main components in the Software segment. These are the OS & the UI. Both of these have their own importance in smartphone performance.

OS refers to the Operating System that your device is running on. In this case, Android is the OS of your phone & it's version will indicate to the generation of OS (Andoid) your device is running on. So, if you're on Android Nougat, your OS version is either Android 7.0 or 7.1.1 or 7.1.2 . OS is responsible for all the tasks that is being done by the Hardware to make your phone perform all it's functionality. So, the OS version you're running on determines how well your hardware is being utilized.

Choosing the right OS is easy. Look for the latest OS available when you buy a new phone. If you can't get the latest one then, go for a generation older OS. For example, if Nougat is the latest OS available & you can't get that in your desired device, at least look for the previous gen Android 6.0 Marshmallow. New OS versions come with better features & optimization. So, newer the OS version, better the performance right ? Well, kinda. UI has a part in here as well. So let's discuss about UI next.

The User Interface (UI) can make huge differences in Smartphone Performance. Let me explain UI with a real life example. Relate UI as the clothes you wear. Clothes determines how you'll look like. But also, if you wear light clothes you can work faster & easier. But, wearing heavier clothes will make it harder to work & so, your performance will be slower.

UI makes your OS work the same way. A Heavy UI will limit your devices performance while a Light UI can bring out the maximum performance your device can achieve. So look for a Lighter UI for your device. Ligher UI can be identified with Shorter Animation Times, Less Customization over Stock Android & Less Preloaded Bloatware. But, in case you want a ton of customization features in your UI, you have to go with a Heavy UI instead.

The good news is, there are many optized UIs now who spot a perfect middle ground between Heavy & Light form factors. These bring good performance with some useful customization features on top of it. For example, the current gen ASUS ZenUI belongs to this category.

So, the combination of OS & UI determines how much of it's power your Hardware can bring out. That's why the Software of your device is also very important when it comes to performance.

Now, as I was talking in the start of this article, We have diiferent type of users where "Normal User", "Mid-end User" & "Pro User" are the main differentiable groups. All of these user types can use my Performance explanation to determine what kind of device they really need.

Checkbox all your needs & determine that what kind of user group you fit into. So, depending on my above Performance Explanation you can now confidently decide which Smartphone to buy based on your needs & your budget.

That wraps this article up. Feel free to ask your queries & share your thoughts in the comments section below. Also, share this article with those people who may get benifited with all this knowledge. Thanks for reading & stay tuned for upcoming articles of the explained series !

Also From The Explained Series !

Smartphone Displays Explained - IPS vs. Amoled !

Very good topic Ronit! One thing I would like to mention that This is a 14nm Processor is the fabrication specification and it not only reduces the power dissipation but also the overall cost of IC Fabrication.

koushikhalder posted on 2017/8/17 15:33
Very good topic Ronit! One thing I would like to mention that This is a 14nm Processor is the fabric ...

Hope this is useful