IEEE 1394 (aka FireWire) and USB stem from a time that most computers had significantly less than 4GB of memory. As a result the designs from these old times is sometimes limited to 4GB internal address space.
What does this mean for you?
- if you have less then 4GB memory things just work.
- If you have more then 4GB memory then things either do not work at all, or an extra in memory copy is needed, slowing things down.
Think of it as someone who has learned to write to single digit pages (pages 0 to 9). If you ask them to read from page 11 then someone else first has to copy page 11 to a page in the range 0-9, and then the person can read it. This double buffering slows things down.
How does this apply to you?
You wrote you have the 64 bits version of win7. That one allows you to use more then 4GB memory. However you did not actually post that. thus:
1) Please add to the OP how much RAM you have.
2) Try booting the system with 4GB or less and see if the problem persist.
If the problem goes away, install thos patch (as already mentioned by Lloyd).