Apps crashing a lot on iPad 2. Any fix?

I've had this iPad 2 since Feb. 2014. I plan on getting a new iPad in a few months, but right now I'm curious why my apps have been crashing a lot lately. I know apps aren't really made for it anymore, but it seems lately things crash more than usual. Facebook will crash if I watch too many videos. My games like to crash if things get intense. If I restart it apps work fine for an hour, but after it'll start crashing again. Could it be my storage space? I only have like 1.1Gb free space (it has 13gb total). I'm going through my pictures and deleting some things (takes up almost 3gb). Could this help? I also don't have any apps running when I'm on something else. Whenever I'm done with an app I always swipe it up,off the home screen. So is there a way to improve its performance? My iOS version is 8.4.1. Won't update to iOS 9 since it ruins iPad 2s I hear.