I was just playing around looking at locationless cache logs with Greasemap enabled. On a cache with 900 or so finds my memory usage went from the normal 382MB to 1.8GB. I currently have 785MB of physical RAM so this used a lot of virtual RAM and slowed the system dramatically.
I have now disabled Greasemap would suggest that anybody with Greasemap enabled should disable it before looking a logs with a lot of finds.