I don't think solving the USB issue was a total waste of time. Knowing what is going on is always valuable. The "My USB throughput is not what it should be...

I don't think solving the USB issue was a total waste of time. Knowing what is going on is always valuable. The "My USB throughput is not what it should be... Oh, well. Must be the USB cable..." attitude is something that can bite you later, because it can be the symptom of a bug (e.g. packets lost because of a buggy ISR) that's just waiting the worst moment to show its ugly face.