How much memory do you have installed ? Did you checked to see what allocated largest part of the memory.
Y'all people crack me up...every little issue you assumed is a windows issue...and not at all something to do with you particular system and what is on your hard drive. Right now with an MMO open, 5 chrome tabs, Advanced Combat tracker running, teamspeak...and everything else 24% memory being used I am not even sure but I would guess around 200+ processes are running. /edit and oh I have 16 gigs of ram. I actually have 4g in use, 591 megs modified, and 3g on standby. I am not a fan of windows...but it is what it is and what we have.
The deal is that there are certain apps which aren't working properly with the new build. The Weather Channel App is one of them. Memory will go sky high. Other things can affect it also. You can't be sure which one will be the trigger, it will just happen. But, when it does the Runtime Broker is always the one eating the memory. Close whatever you are running, then close runtime broker in task manager. Your memory will return to normal.
Do you have any ads blocker with firefox ??? it is them who eat lots of memory on top of firefox ... i am on 565 with waterfox + ads blockers ... it eats 465 megs of my memory, it is not windows problems, but since i have 32gigs to spare I close everything and its the svchost who eats the memory, 120 megs in my case.