Hrm. I've looked at deopts before, and I may be wrong but I think they aren't the issue. As I understand v8, it's normal at startup for hot functions to go through the opt/deopt cycle several times as the engine learns about them - and once a function does it too many times, it gets deopted permanently.

For this reason I always let the game run for 10-15 seconds before I profile, figuring that by that time most of the opt/deopt churn will be finished. And this (very useful) script seems to back this up - I get output like yours at startup, but if I wait a while and then rm the output files, further output is relatively minimal.

So I'm inclined to think that opt/deopt stuff isn't the issue, and there really are lots of JS heap objects getting allocated somewhere. At the same time though, when I used Chrome's built-in memory profiling I see a bunch of deopt-related strings, so maybe I'm way off base. If anyone sees what I'm missing please do clue me in.

(Also: great tip on the script!)