'mac pro mid 2012' slower than an 'i7 imac late 2012'?

I have a mid 2012 mac pro which has: 2 x 2.4 GHz 6-core intel xeon processor, 2 x 1gb ATI Radeon HD 5770 graphics card and 28gb ram.
I also have a late 2012 i7 27" imac which has : 3.4 GHz intel core processor, 2gb Nvidia Geforce GTX graphics card and 24gb ram.

But why does it feel as though the imac handles video editing in FCPX a lot quicker? I expected the mac pro to blister through editing however it seems sluggish in comparison to the iMac. Could it be to do with harddrive use perhaps? Any ideas?

There is specific software technology in FCPX that makes use of specific processor that are in the iMacs and Macbook Pro's that aren't in the older Mac Pro's.
That's why it feels faster.

You can read about this somewhere on the Apple FCPX pages.

A lot of people have been coming to the same conclusions.

Yup, and those iMacs are no slouchs!
My rMBP slays my old Mac Pro...

I have a hunch this is one of the reasons. The Xeons in 2012 were just updates from 2010 which didn't have AVX capabilities.

www.apple.com/finalcutpro/all-features/
Grand Central Dispatch
For even more speed, Final Cut Pro utilizes the AVX capabilities of Intel’s Sandy Bridge and Ivy Bridge processors.