I just defragmented my MacBook pro with iDefrag – and the simple answer is that I should have gotten this a long time ago. I do a lot of video and a lot of development and my drive runs between 75% – 85% full all the time.
I used the variant of iDefrag that makes a boot ROM and then can totally defrag my disk. It was horribly fragmented – particularly the free space.
My main issue was that I could not keep up with capture (on a dual 2GHz Intel!) and lost frames.
Once iDefrag came up it was clear – there was no real clear free space so it was seeking like crazy and not able to keep up with frames – reminds me of the old days with a PC :)
iDefrag of my 90GB out of 120GB took about 5 hours with a cool picture all the time so you don’t get nervous. On reboot all is well. I will likely defrag after every large media project from this point forward.
I really need to get a 200GB drive to do all this video :)