The current heavy_compute shows bevy as about ~2x slower than specs. However, parallel_light_compute (see discussion) shows bevy is very sensitive to batch size and can be anywhere up to 10x slower than e.g. specs.

In my results (where I merged your and other forks and updated all libraries among some adjustments) bevy is only 2x slower than specs in parallel_light_compute and actually faster than the other libraries. It might be sensitive on thread count as well (I ran it on a 16c/32t system), or the situation improved drastically between bevy 0.5 and 0.6.

Thanks for looking!

However, a note: bevy is extremely sensitive to batch size, while other libraries don't need a batch size to be set. Your file shows a batch size set to 1024. In the discussion I posted above, you'll find the following table which shows bevy scaling with batch size:

On my pc, 1024 was the optimum batch size for bevy. For comparison, specs was 108.00 us, so bevy was about ~2x slower than specs. However, in the worst case scenario of unoptimised batch size, bevy remains >10x slower (hence my numbers in first post). I expect the 'ideal' batch size is both hardware and System dependent, and the optimum will be rarely achieved.

(Disclaimer: my tests are still for bevy 0.5 and I didn't get time to run comparisons for 0.6 yet! but my understanding is the parallel performance did not change from other discussions).