Strange bedfellows, ThreatFire controls/conserves RAM!

Years ago I installed a little application called MemInfo that sits in the notification bar and monitors RAM usage. With MemInfo I discovered that an AVG Anti-Spware two minute memory scan restores leaked RAM. Apparently no one knows how it does that but I've renewed my subscription twice since the ewido days because of that feature. So the other day I install the Comodo v3 Firewall and while online and sandboxed (Sandboxie) my comp basically stops. I try several more installs over the next few days and the same thing occurs. I'm very careless about disabling security applications while installing software, as is normally recommended, since I usually get away with it. So I try a fourth install Thursday of Comodo with NOD32, AVG A-S and Windows Defender disabled. I also installed it without the Defense+ component for the first time and still have not enabled that feature. Firefox sandboxed is quite normal now, although I'm not sure if it was the install procedure, the install without Defence+ or both. Anyway, so I see the thread here today inquiring about Defense+ and ThreatFire and decide to give TF a run. Had some kind of pc lockup after a required reboot during installation, however, since that time it has been running flawlessly and my pc is as fast as ever. The most interesting thing though, is the fact that memory uses by all of my processes have kind of been frozen. Normally, in about three hours of use, even just surfing, the percent of 1G RAM usage will climb from a basline, after an AVG A-S memory scan, of 27% to the low 40s. Firefox right now, with seven active extensions, is only using 38,000kb. Overall MemInfo is showing 34% in use. Go figure!