I play with gamepad and have had no issues with it since U25 even if I use KB/M and go back to the gamepad. (also no skill delay issues that you seem to have mentioned)
If you are having performance issues in the game you should start by disabling all your addons if you have some then verify if the issue persists. Many addons have been causing problems since U25. Quite a few have been fixed but it is likely that not all of them have been.