I must say - that kind of perf is superb, though top percentile and averages aren't super representative of the average customer's experience. What are your tp50 and tp90 like?
Your sub-150ms invalidation is equally if not more impressive, especially if you're talking about multi-region invalidation.
TTFB at the 50th hovers around 175 microseconds, 75th is at 250 microseconds, 95th around 450 microseconds.
As for the purging stuff, I do mean cross-region. So, it depends upon which node receives your purge request. 150ms is average, but really it's "network latency plus a millisecond or so".
Wait, so 95% of your customers experience a TTFB of less than 500 microseconds (tp95 of 450 microseconds)? I just want to make sure I'm understanding you correctly. Because that's awesome.
Your sub-150ms invalidation is equally if not more impressive, especially if you're talking about multi-region invalidation.