What is the best file system and allocation size for a USB flash drive?

"As stated in the comments of the other answer suggesting using ATTO Disk Benchmark, I don't have a way to analyse the performance of ext2 (with ext2 IFS for Windows) on my USB drive.

So I gave it a try: I formatted using ext2, put my firefox profile on the flash drive, and then I did some surfing.

Surprisingly, ext2 behaves MUCH better than FAT32, NTFS or exFAT. Using one of these three filesystems I had constant freezing and unresponsiveness when using Firefox. Using ext2 there are still a few stutters but overall it is much more usable than the others. I have no idea why.

I'll mark this as accepted unless someone comes up with a better answer (other software to benchmark filesystem performance or an explanation as to why ext2 would be better)."

Another idea: http://www.romexsoftware.com/ offers you a RAM disk. That software has an option to store / restore the current state of the RAM disk on shutdown / startup. -> Put that RAM disk image onto your USB stick?