Possible iPhone 4s battery fix?
I wanted to contribute this to the community as a possible fix for people who own an iPhone 4s and have experienced rapid battery drain after one of the recent iOS updates. The fix seems to have worked for me.
I had searched everywhere on these boards but found no solutions - my 4s, which had always worked fine, was suddenly draining in 4 hours with little or no usage. Then I noticed that my MacBook pro one night had its fans on quite loudly while I was not really using it. I checked the running processes and found that Safari was using a lot of CPU time. Looking into it further and searching the web for others with this problem, I discovered that it was my Reading List in safari which was using a ton of CPU.
I had noticed before that I use Reading List in a somewhat unconventional way - I drag a lot of pages in there, using it as a sort of "bookmark list" for interesting pages. It took me a while to realize that the OS caches those pages for offline viewing and keeps them updated. It seems certain pages were choking this system for some reason, using a lot of CPU and memory.
After i noticed noticed this, I completely cleaned off my phone (again), reset all settings, then removed everything from my Reading List. Amazingly, this seems to have solved my battery problem. I can imagine this won't work for everyone, but I thought I would mention it in case others use Reading List in the same way.
iPhone 4S, iOS 8.1.3