PTP seems to be consuming a ton of memory after running for extended periods. After loading to the desktop and initial drive activity has stopped, I'm sitting at about 1.5GB of my physical 6GB consumed. Without using the machine at all, I can come back about 4 hours later and the machine is at about 4.5GB of RAM in use. PTP is configured to process jobs only after 1 min of idle time, but this large block of used memory will not clear unless I fully exit PTP.
I'm running a core i7 920 w/ 6GB RAM on Windows 7 build 7100.
different projects can use different amount of memory. and by default projects rotate every hour. so if you go away and then come back, you may see a very different memory picture.
also, i think you have a quad core system, so i think your app may try to run 4 tasks per project when running (if 4 tasks are available) -- and this will use up 4x as much RAM. there is a preference to limit to a lesser number of cores.
so it would be useful to check a few times, to see if memory use continues to grow over time or if it goes up and down. as your projects rotate.
also: what projects are you running?