USB bandwidth on TX2

we design 2 USB 3.0 on our carrier board ,both of these 2 USB were output form TX2 directly. We found when we connected 1ch USB3.0 Camera(Basler) the frame rate was up to 155fps,but when we connected 2 ch USB camera, the framerate decreased to 113fps & 119fps.
does anyone have idea on this case ?
thank you

Hi,
For more information, please specify which USB ports are used on your custom board.

Plesae refer to following Sch. of USB
you can see the USB was output form TX2 directly and no Hub switch in our Sch.



TX2_USB.jpg


USB-02.png

TX2_USB.jpg

Hi,
Please profile via tegrastats in running two cameras. Probably CPU loading is close to 100% in the case.