I wonder if there's any way to improve BitTorrent performance by putting any cache on a USB stick, like the ReadyBoost in Windows?
ReadyBoost was an improvement because it put files in sequence on the flash drive; therefore, it would sometimes be faster than an HDD. 'Sometimes' because it offered you a test to see if ReadyBoot would improve your boot time, and, sometimes, it told you not to bother. Now, HDDs are faster than USB2 flash drives.
Your cache files are not in linear sequence, in the order they must be accessed to hasten startup. And, by now, odds are you have a system drive which is faster than the typical HDD when ReadyBoost was hot stuff.