Anyone else's iPad 1 constantly crash?

I'm an certified AppleTC and work in a University and have tried everything to get our companies iPad 1's to stop crashing when running the latest 5.1.1 iOS. I have wiped them, restored, set up as new, hard reset, limited the amount of apps etc and have come to the conclusion that it's the OS that is at fault since all our iPads 1 do exactly the same when running 5.1.1.

All the iPad 1 we still have running version 4x iOS work fine, don't crash, are fast and snappy unlike this one I'm trying to type this on which can't keep up with my typing and is frankly painfull to use.

Telling my bosses that the solution is to buy new iPads dose not go down very well when the device is well looked after and is not physically damaged.

I know that this is due to lack of memory but I wish the last iOS for this device was a stable one that allows the iPad to be used for its primary task of surfing the web and social media without constant slowdowns and crashes or at least provide a mechinasm for down grading to an earlier OS that works.

Unfortunately I'm losing the battle to recommend these at work and they are now switching to MS surface and Nexus devices.

So Apple, if this is a ploy to force upgrades to newer iPads, then this is a floored strategy, you are simperly going to loses market share due to a making the final iOS for this device a bad apple.