Quoting Snarkasm

NTFS doesn't make the drive slow. It's a different filesystem, that's all, and it lets you put files larger than 4GB on the drive.

It will slow down a flash drive Snark. Most flash drives, due to the nature of the Nand, will find FAT32 the fastest/speediest. Now, if you can get it formatted NTFS with 32K blocks.. that should be close to the same speed.