Ya if you allocate/deallocate onto a stack, the most recently freed memory is more likely to be hot in the cache for the next allocation, reducing overall latency.
It'd be interesting to see a version of that graph with just Episilon/Shenandoah. It's hard to tell but it looks like Epsilon may actually have lower average latency but Shenandoah may have lower jitter & max latency.
It’s something I do all the time in C++.