Would defrag utility help stop freezes during play back?


I have a JVC TV with a built in PVR, think its an old Humax 9200. I found after a while I needed to re-format the disk to help speed up access.
So was thinking that a defrag utility would help with playback freezes on the HDR-Fox T2, especially when the box is doing extra jobs like decrypting files, playing back and recording.
Looks like it's unmount the file system, Tar the entire thing to another drive, mkfs then copy it all back. Not exactly an 'on Disk' solution though. Oh and by the way everyone seems to agree there is little advantage in doing a defrag.