🐛 Bug Report — Chrome dev tools profiling very inconsistent

Possibly related to #5301

Some performance profiles seem to be completely missing certain spans, but it's not obvious unless you take the performance profile again and get lucky (and even then it's hard to know if there's anything missing).

This makes it really hard to know whether any given performance profile is as "complete" as it can be.

Example profile:

Ran the exact same workload and took another profile:

Notice the first profile goes no deeper than `flushSubtree`, making it appear as though it's the ultimate culprit, whereas the second one clearly shows that that's not the bottom of the stack where the work is being done, and it's functions like `writeChunk`, `writeStringChunk` and `encodeInto` that should be below it.

Something's getting lost somewhere, sometimes.