My Computer
At a glance
Windows 7 Ultimate x64
- Computer type
- PC/Desktop
- OS
- Windows 7 Ultimate x64
Hmmm...I'm not sure what's fastcopy, but when you say copy/paste multiple files, you are pasting into an external source I presume? If it's within the system itself, I suggest you do a check on your hard disk.
http://www.sevenforums.com/tutorials/139810-sfc-scannow-run-command-prompt-boot.html

I think you've missed the point.I use Fastcopy only to show that my hdd can reach full write speed under these circumstances.If every windows user will be able to boost their file copying performance by 100% and all they have to pay is a few more clicks,this software would be much more famous.Well then. I dont see theres a problem with explorer since youre using a third party software to copy files faster.
Its like an athlete on steroids and allows him to run faster, or in tech terms, a normal computer using readyboost to speed it up more.
Just for some advise. Since you have SSD and HDD both internally I suggest that you can actually reformat your computer and make it such a way that your windows 7 is on SSD and your data files on HDD. That way your OS will boot up faster since its on SSD and wont have hard disk problems on the long run.