Speed up tinyusb CDC serial transfer rate on ESP32-S3 (IEC-93)

[Superberti]

Answers checklist.

• [X] I have read the documentation of the component in question and the issue is not addressed there.
• [X] I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

Hi,

I'm using an ESP32-S3 on ESP-IDF on the release/5.2 branch. I made some tests with the tinyusb CDC serial profile but I was not able to get read transfer speeds on the native port (pins 19/20) over 50 KiB/s. The theoretical maximum rate should be something about 1 MiB/s in this mode. Regardless what I'm doing (larger buffers and FIFOs, using tinyusb with or without tusb_config-h), it had no influence on the transfer speed. So it seems that the speed is limited in some other way. The USB port is connected to a C# test program which sends out the data as fast as it can, so this should not be a problem at all. Any ideas how to speedup the CDC read speed?

Thanks and bye, Oliver