Phone slowdown after Jelly bean update I have Sony Xperia P phone which is updated to Jelly bean when they rolled out the update. It came with Gingerbread and I updated it to ICS, as soon as I got it. It was running great.  

But it's started to give me problems since I updated it to Jelly-bean. Even the recent minor release didn't fix the slow down issue.
To give the example of slow down, I am getting Slow FPS and sometimes frozen screen for half a second whenever I play a game. Slow FPS is universal for all the apps. When I had ICS I could play games like Subway surfer without any problem, and now I can't play it due to low FPS. Sometimes the System UI gets killed, whenever I start any normal game (such as Samurai v/s Zombie defence).
I don't know if it's a universal problem or just my bad luck, but one of my friend who bought the phone with me, is facing the same issue too. Any idea how can I make my phone run fast again?
There are some bugs reported in the Xperia P Jelly Bean update 6.2.A.0.400. Even if it is suggested to perform a factory reset, the problem has not seemed to have fully solved. 

So your problem will not most probably be fixed until Sony releases a new version with bug fixes (and it might take some time)

Note: Since you are mainly concerned with your gaming apps, you might need to check the incompatibilities from the Google Play Store.