Storage Ridiculously high response time and poor performance on HDD

Hello all,

I've looked all over the interwebs and seen a thousand and one different opinions on this. Thought I'd ask for yours.

I've got an SSD as my main boot drive and a 2TB Western digital HDD as my storage drive (link for my HDD here).

Since I've updated to Windows 8.1 (Happened on 8 as well), my response times for the storage drive on windows task manager are in the 1000's of milliseconds and the performance of the drive has went down. When unraring a file for example I can no longer watch a TV/Movie that's on the same drive as the throughput is totally choked and I get stuttering/hitching.

Is there anything you would suggest trying? One of the top recommendations is to switch my motherboards SATA mode from AHCI to IDE. However when I do this, I can't boot into windows and some have advised this may impact the performance of my SSD.

Any suggestions would be appreciated