CS6 is neither optimized for Retina, nor supported for use in El Capitan. Basically, you're lucky it's running at all -- Many users who try have much worse trouble.
Is there anything I can do...?
You can subscribe to CC. The 2014 release seems to be pretty stable on El Capitan. Many users have no problems with CC 2015, either, but there are plenty who do.
If you want to stay with CS6 you can either live with things as they are or roll back your OS to a previous version. There will be no updates for CS6.