Bubble Game - 60FPS, 4.3mb image memory, 15-20% CPU
Jumble Art - 60FPS, 9.4mb image memory, 14-15% CPU
Both tested in Firefox with debug mode on a laptop with 8GB DDR3 RAM and an Intel i3-3110m CPU.
So your games run fine, but the C2 editor does take up 1.3gb memory when opened Jumble Art (and around 200mb when opened Bubble Game). It might be a bug that causes this, so I suggest you file a bug report and see what the Scirra Team has to say about this.