For example, the game logic loop cannot be offloaded to the plug-ins. Simple path-finding is expensive; updating the physical properties of thousands or tens of thousands objects 60 fps is expensive. These kinds of game don't exist because Javascript is not fast enough.
I'll give you another example. That was one game I have in mind that involved simply pixels. 100x100 grid is 10K objects; 400x300 grid is 120K objects. 40fps x 120K is about 5M objects/second. Each object involves however so much processing. Doubling to 800x600 gives 20M objects/second. It adds up fast.
