Why are Chrome V8 garbage collects so slow?

I work on a web multiplayer FPS game, and some users report huge hitches that are always Major GCs.

Garbage Collect Time

In this case, the garbage collect is 415ms, which is absolutely unacceptable while playing a game.

The JS Heap isn’t incredibly large, and in Chrome’s Memory tab it seems like the largest things getting allocated are “compiled code,” is this a Chrome bug or is there a better way to test why the GC is taking so long?

Memory Allocations