I've done this before for plenty of tight loop code. Nothing irks me than staring a profile and seeing "Major GC" multiple times in the middle of a big algorithm.

It's certainly not helped by the latest language fads just completely flooring the GC gas pedal; special mention should go to for...of creating a brand new object for each loop iteration. That's usually the first thing I rip out of tight loops.

A bit of care can make this stuff go 3x fast on PC, and I've gotten completely unusable experiences on mobile (most websites) to be 30-40fps.