After Effects very slow
There are many different reasons After Effects slows down. The link will show you some ways to fix the problem.

Useful Website

It's says to:


"Make sure that you’ve installed the current version of After Effects, including any available updates. To check for and install updates, choose Help > Updates."
"Make sure that you’ve installed the latest versions of drivers and plug-ins, especially video card drivers. To download updates for drivers and plug-ins, go to the provider’s website."


There are many more too.