Is there some rule-of-thumb related to stub lengths (especially for the USB 3 differential lines)? Maybe compensation with some of the CYUSB3326 configuration?
We have a couple of optional populates. We have minimized the stubs, but when an end device is the target we have small (<5mm) stubs.
-To reduce the stubs, you can route the lines to the bottom layer using double pair of vias instead of a single pair.
-In case you are unable to avoid stubs, you can reduce the pcb thickness as well.
Please refer to the Application Note for further layout guidelines.