Recently I've noticed the same problem on my win xp system. After a reboot, it's using 116 meg working set, 208 virtual size (I use sysinternals procexp to monitor). AFter a few days w/o rebooting, it's about 300 meg working set with virtual memory at about 500 meg. Every so often I go a week w/o rebooting and the last time I was running low on memory, it said it was using 500 meg working set and nearly 1 gig virtual memory.
I find just rebooting every few days is the answer. This is my main system, where I have 3 1080p monitors and lots of hard drives. I've built a new system running windows 10 that has 16 gigs of ram and it's so fast I can use vnc on one monitor (from xp) where I now run firefox (another memory hog) on this win 10 system. Eventually I'll get all my programs ported to win10 and just use the built in virus program. I saw the post on how to try to fix this problem with beta updates etc. but I'm not going to mess with that. I'll just reboot every few days.
But it was good to see I'm not alone on this.
