USB 3.0 Western Digital 1tb EX HDD, extreme lag [stop and go]

Hello community of helpers!!

today my problem is with my external drive. Its a 1tb Passport by Western Digital.

The harddrive is partitioned into 2 parts, filled with movies and tv shows. The drive is aprox 78% full.
The format is Fat32 [ps3 compatibility]
I have the latest drivers installed for the USB passport
the USB controller for my mobo is up to date, latest firmware
I have tried both USB 3.0 jacks on my comp

The drive always shows up and is visible through My computer.
I have defraged the disk and run the chkdsk, both completed successfully.

while watching the resource monitor i can see that the drive activity revs up to 100% and stalls there for a while freezing movie or even music playback. Then a few seconds later it resumes at a normal speed. The same thing happens when i run a virus scan or copying and pasting either to or from the drive to my local HDD [internal]

running ATTO disk bench and watching resource monitor tells the tale:


^^ you can see the "stutter" i outlined before.

hope you guys can help, i've got almost a terabyte of media id rather not have to move -.-


comp specs:

p8p67 le
i5-2500k @ 4200
ocz vertex 3 128gb sata 6.0
wd 500gb caviar blue sata 6.0
hd radeon 4670
coolermaster 912
8gb patriot sector 5 @ 1333
750w OCZ zt series modular PSU


cheers,