I believe I found the optimum combination to make my iPad2 as good as before, maybe not 100% but at least 80% of what it used to be.
For those who upgraded to iOS 8.1.1 but still facing sluggish and freezing issue, this may help. Even those who do not wish to upgrade to iOS 8.1.1 but want to get a much better performance, this could help as well.
1.4GB of free space is required to upgrade to iOS 8.1.1, As such, I was forced to delete some files. Previously only a few hundreds MB of free space available.
Guess what, I noticed at least 50% of speed improvements after I got 1GB of free space, even before I upgraded to iOS 8.1.1
Once I upgrade to iOS 8.1.1, I got at least 80% performance improvement.
Previously in iOS7, a few hundreds of MB(or even less than 100 mb) is good enough for smooth performance and speed. I believe in IOS 8, a minimum of 1GB is required.
I am happy to get back my 'stolen' iPad2. I know how frustrated using a sluggish iPad2 that keep freezing, feel like smashing it onto the wall.
I guess Apple did test on iPad2 before iOS8 release and did not notice any performance issue simply because the tested device has plenty of GBs left. Apple does not realize iPad2 users has a choking amount of apps and data, with almost no free space available.
So guys, try to make at least 1GB of free space on your iPad2. Please give your feedback if this work for you.
If it works, I guess it is about time for Apple to give extra caution/statement on the upgrade to iOS8:-
"Older device need at least 1GB of free space for optimum speed and performance."
But I still notice some issue when downloading or upgrading apps. It is slow and sluggish when the apps is in the installing phase. The screen may freeze and the installing take ages. But I can live with it because you're not installing a new app everyday.