Actually USB debugging is for writing your own applications on your phone - you can single step through your own apps to see what they're doing etc. when it's enabled. The reason I've heard cited for why USB debugging speeds up the phone is that it kills some processor intensive task that slows the phone down. Probably something to do with HTC Sense/Sync.
Yes, USB debugging can also be used by programmers to debug their programs, but it will also debug the phone itself. If that processor intensive task is on for no need by the phone, then shutting it down is also a form for debugging to optimize the system
Upvote
0