Win7 Slow File Transfer (FIX)

Problem:
Windows 7 transfers files very slowly with 100% CPU usage and system slows down to a crawl. This problem is consistent with transferring files across local drives/partitions as well as transferring files across the network. Transfer speed is only around 7 MB/s which should be around 30-60 MB/s.

Solution(s):
Set Power Options to High Performance
Go to the Power Options in Control Panel (Control Panel\All Control Panel Items\Power Options) and set it to High Performance if you are using a desktop computer. For laptops, set it to high when plugged-in; there should be manageable rules for power consumption that you can set, just fiddle around... because setting it to high will drain the batteries faster if not plugged-in, or you can manually set it to high only when transferring files.

My Windows 7 is set to Balanced (Recommended) Plan in Power Options by default even if I installed it on a desktop computer. Balanced or Power Saver plans tend to minimize power consumption on devices that support it, and that includes your hard drives, network and USB ports. This seems to fix the problem with very slow transfer speeds both locally and on the workgroup.

Install Mass Storage Drivers
Download the RAID (Mass Storage) drivers for your motherboard. Windows 7 has probably installed a generic driver for you, which probably just emulates mass storage functions for different manufacturers thereby causing a heavy load on the processor and decreased file transfer speeds.

I did not install the raid drivers for my board since there were no unknown hardware in Windows' Device Manager so I've experienced this problem myself. After installing the updated RAID drivers, file copy is now about ~45 MB/s and CPU usage is very minimal.