Some apps are too slow on my phone. What can I do to fix this?

Granted, at 2GB ram Mediatek MT6737, I don't have the fastest phone but why is it that I have 2 apps that are very sluggish while others are more, seemingly, graphic intensive yet much snappier? What can I do (besides the obvious - clean up the phone) to speed up these apps. I'm rooted. Like this app: https://play.google.com/store/apps/details?id=com.blockfolio.blockfolio