Help Samsung Galaxy S2 started to be verry slow and laggy

[piotrchmiel]

It's almost 2 full years since we bought our Galaxy S2s and both started to be very slow and laggy. Especially my wife's phone. I uploaded video to show you guys what exactly I mean. I would like to know what can be done to solve this issue. When I went to T-Mobile's store I was told that due to changes I will no longer get new phone cheaper or for free. Now I have to pay full price and long term customer doesn't mean a thing. I don't have money for new phone and I didn't think that Galaxy S2 would be piece of s*** so fast.
I've already formatted both phones and even deleted all text messages but lagging is the same.
Do you have any ideas what to do to fix this issue?

https://www.sendspace.com/file/dl3409​

It alsoo freezes from time to time for no reason. I don't have many many apps, only few widgets and this phones was lagging even after formatting.
http://forums.androidcentral.com/newreply.php?do=newreply&p=3727109&noquote=1

 

[Rukbat]

1) Which version of Android are you running? (Remember, it was designed to run Gingerbread, 1GB of RAM, 1.2GHz CPU). Running a more current version of Android is possible, but you're not going to win races hauling house trailers with a Porsche. The phone is over 3 years old. If you want a snappy phone running a current version of Android and current apps, it should be replaced about every 2 years.)

2) Check the apps you're running at boot (there are free boot managers on Play). Don't run anything the phone doesn't need to operate. (If it's loading a browser at boot, that's a waste of RAM unless you always use your browser when you turn the phone on.)

3) Make sure you have a few hundred MB of storage free. The apps need somewhere to store data. (Android apps are subject to be killed at any time, so any change in data has to be saved when it changes.)

 

[piotrchmiel]

Android 4.1.2

 

[piotrchmiel]

I forgot to add that my galaxy s2 works almost without any problems or lags.It's only about my wife's phone. And this is why I think these issues are fixable.