Guys from mikrotik knows about issue and working on it..I am having the exact same problem with my background image. Worked well in b7, but anytime I resize or move, CPU goes to heck and the Dude locks up.
Can someone look at the background image rendering? I've about given up and am going to use the grid background for now. This is actually a big bummer, I hope it can be resolved soon!
Thanks!
AdinaNet