Android phones, not talking about the ones that are running stock skins are prone to slowing down thanks to a process called fragmentation. In comparison, users have rated iOS as being more optimized but on several occasions, Apple has been blamed for slowing down iPhones and iPads through software updates.
However, it looks like the problem could be related to hardware too, as a Reddit user provided all of his research, also mentioning how he ended up speeding up his iPhone 6s just by changing the battery.
“My iPhone 6S has been very slow these past few weeks, and even after updating multiple times, it was still slow. Couldn’t figure out why, but just thought that iOS 11 was still awful to me. Then I used my brother’s iPhone 6 Plus and his was… faster than mine? This is when I knew something was wrong. So, I did some research, and decided to replace my battery. Wear level was somewhere around 20% on my old battery. I did a Geekbench score, and found I was getting 1466 Single and 2512 Multi. This did not change wether I had low power mode on or off. After changing my battery, I did another test to check if it was just a placebo. Nope. 2526 Single and 4456 Multi. From what I can tell, Apple slows down phones when their battery gets too low, so you can still have a full days charge. This also means your phone might be very slow for no discernible reason. Check your Geekbench scores and see what you get if your phone is still slow!
TL;DR Apple slows down phones with low capacity batteries, replacing it makes them full speed again. Check Geekbench Scores.”
If you can change the battery then even you too will be able to experience the same performance as the iPhone 6s owner. The problem seems to be associated with the battery. When your smartphone’s battery gets old, it starts to degrade, eventually displaying a battery life from the phone that is below satisfactory for the user.
With the release of software updates, the iPhone’s processor clock speeds might be slowed down so that it forces the battery to consume less juice, giving you a performance bit but giving you the same battery life as when you first unboxed the phone for the first time.
So long story short, if you are an expert in replacing batteries in phones that feature non-removable cells, then you should attempt to replace this battery otherwise let an expert deal with this dilemma.
