Okay, i was actually expecting a small bump, as that would have moved some of the MUSB transfers from cpu cycles to direct DMA transactions. I guess even with MUSB_DMA (it’s broken for generic use cases), didn’t help…
The only thing left i would personally try, would be the bone kernel branch, as these are SMP disabled, pretty much optimized for am335x as much as we can. Debian 10.x/11.x Kernel Updates
sudo apt update ; sudo apt install bbb.io-kernel-5.15-bone
Regards,