Re: "Buggy" USB Transfers
i'm running x64 KDE as well. I only have USB problems if i use my 16gb flash drive. It won't correctly transfer things, and locks up the notifier. Even formating it with gparted doesn't work. Put in windows 7 works fine, but my 4gb and 8gb both work flawlessly in BT5. So yours probably could be an issue with the size of the drive / improper formatting.
Re: "Buggy" USB Transfers
Hello, thought I would chime in as I know a bit about USB. I am however still a n00b to back|track so take any thing I say about that with a grain of salt.
Firstly, were you moving a folder full of small files? Or just a few big files? It takes significantly more time to move a bunch of small files (Read or Write) for the same reason fragmentation slows down an HDD. Try a few times with an .ISO or two and report back what happens if you would please. Also, some setups have the information stored to a shadow directory and are only actually transferred to a thumb drive when you tell the OS you want to detach it. On windows this is the reason for the “safely detach” USB tray icon. (even though the actual shadowing is off by default).
Secondly, are you sure your thumb drive is USB 2.0 “High speed”, and not just USB 2.0? That was the big bait and switch when USB 2.0 came out. Being “USB 2.0” means being compliant to USB 2.0 specs. But the specs have provisions for 1.5Mbps, 12Mbps, and 480Mbps speeds. So a device can be USB 2.0 and still be slow, and they often were. If you have an older thumb drive you should check this.
Also as hardy as thumb drives are, FLASH technology it's self, or more specifically, the transistors that make up the memory storage elements. Have a limited number of uses before the insulation of the floating gates breaks down, or the charge “sticks” inside the gate. In lay persons terms, the do ware out eventually.
Now, most good thumb drives have ware leveling and error correction built into the interface chip of the drive it's self. Which makes this scenario unlikely for you. However, there are things one can do that will accelerate the degradation process significantly.
If you use your thumb drive a lot, use it as a boot drive, and/or leave it in a lot over night. Routine house keeping tasks like logs, av, scans, and such can constantly read and write to the drive. Also if you ever left your thumb drive in your clothing pocket and it went through a laundry cleaning cycle. The heat from the drier prolly cut the life in half if not more. And definitely so if it happened more than once.
Your best bet as far as the thumb drive goes is to try and use a different one and bench your current one so you know exactly how fast it performs. Also an integrity test couldn't hurt.
And finally, it very well could be a bug in BT5 as it is still hot off the press. But I have not noticed any slowness with it when pertaining to USB so far in my setup.
Hope I was informative.