Happens to me as well. Pretty uncommon though, I can play days with no freeze at all, and once randomly (mainly when screen graphics are heavily loaded with tons of people to display) freezes.
I got no clue for the fade, but I noticed the opposite : sometimes you need to search twice for an improvement to really get it. Blink, for example, or bile bomb, need to be searched twice for them to really be active (happens sometimes)