Really???
Most of these tips DO speed up iPad performance.
How much free data storage space is left on that iPad 3?
Did you free up any internal data storage space.
Do you have anything in iCloud that is activated that constantly is working in the background, slowing your iPad 3 down?
Did you do the hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons?
My performance tips ARE the fix for a slow iPad.
If you used ALL of my performance tips your iPad 3 should NOT still be slow.
Your iPad 3 should be running better than you are still describing.
My wife and I use iPad 2 and 3 models and I have setup all of thess tips on both of these iPads and while performance is NOT lightning fast, these iPads are not running slow by any stretch of imagination, either.
I have an iPad 2 which has much lesser hardware than your iPad 3 on iOS 9.3.5 and it is running better than you describe your newer iPad 3 is running on the same iOS.
Make sure you have covered my questions above and go back and make sure you have done everything listed in my performance tips.
Your iPad 3 performance should be noticeably better.
Good Luck to You!