slow file extraction?

[cinek]

I have an apple SSD in my 2011 mbp, I'm copying a image file which is 820mb, to the desktop and it's only copying at 4mb/s - peak was 4.4mb/s - for me that's really slow for an SSD as with my windows pc where I also have an SSD (sata 2) it's a lot and I mean a lot faster - this is slower the a normal HDD :S

any ideas what's wrong? there's plenty of memory left and the cpu is 94% at idle

edit: copying the file from my pen drive is a lot faster - took about 2 mins whereas extracting it took over 5