iCloud Drive Performance Hit
So far I cannot gather enough information to declare this a wide-spread problem, but in one isolated case I found having iCloud Drive running was causing massive memory and resource usage on a Windows 7 computer.
Pentium P6100 2.0GHz
Win 7 Home Premium 64 bit SP1
4 Gigs RAM
4 Gigs of RAM is pretty low for a 64 bit OS, but that did not explain the frequent Out of Memory messages and extremely poor performance of this computer. While running an AVG virus scan I opened the Task manager and CPU usage was at 79%. The computer was essentially unresponsive. Only after killing the iCloud Drive process did the CPU usage drop to an expected 23%.
Uninstalling iCloud from this computer had the effect of turning it back into a useful computer.