Have a brand new MacBook Pro, and exactly the same problem.
SketchUp was working fine before I went for holidays and when I came back, installed the Mac OS updates and everything in SketchUp became so slow that it is unbearable.

Anybody a solution?

Inio, your fix is also useful in sketchup's update dating 5th of december.
It really speeds up sketchup on the Mac Book, great work!