[jaspitzer]

I have a 500 GB external hard drive that I connect directly into my LG plasma tv by USB. Sometimes when I play movies, the movies lag. I don't know any other way to describe the timing seems glitchy or lagging. Does anyone out there know why this happens?

 

[pip22]

Could be the data on the external drive is heavily fragmented and you need to run a defragmentation tool on it.

I don't think Macs have such a tool built in (at least OSX9 didn't have one) but I understand it runs defragmentation automatically in the background, but I don't think that extends to external drives, only the system drive.

So a third-party solution is required:

Coriolis Systems :: Products :: iDefrag

Defrag Mac drive to increase Mac OS X performance - Stellar Drive Defrag

I haven't been able to turn up any free ones for macs. All the free ones I found are for Windows only.