There is hope.
iPad 2's did not work very well with the early versions of iOS 8 either, and the volume of complaints were far higher, and more vitriolic, than we've had so far with iOS 9.
It performance improved step by step with each point update. You're likely to see the same thing happen with iOS 9. Or so we can hope.
But remember, the iPad 2 is one year older, and one year further behind than it was last year; and it was pretty far behind then. These devices are about as close to dead tech as you can get and still have updates.
I'll be shocked if iOS 9 is not the last version to support them. Then again, I said much the same last year (only I used surprised instead of shocked). So I could be mistaken.