"I recommend using the Reliability and Performance Monitoring Tool to see if your system is memory starved, specifically the memory section. Look for hard faults/sec:
A hard fault (also known as a page fault) occurs when the page of the referenced address is no longer in physical memory and has been swapped out or is available from a backing file on disk. It is not an error. However, a high number of hard faults may explain the slow response time of an application if it must continually read data back from disk rather than from physical memory."