We exclusively use TC-Enterprise Version 4.0 EAP (build 7388) for our CI. We have 29 build configurations currently and we are always adding more to TC.
We all have the Windows Tray notifiers, and after about a week or so it starts to eat up 60-70mb of RAM (as far as task manager is concerned). If I kill the process and restart it, it drops to about 25mb of RAM and stays there for awhile. It looks like you are using the IE ActiveX control, so I don't think the number of build configurations would have a direct impact on memory usage,