Big maps that need more that 20MB are impossible to play couse I get like 0.05fps x.x

I have plenty of RAM avi, when game runs like it should it takes more than 200MB. Other applications don't show this kind of behavior.
This bug is fixable by rebooting my PC but I want ur alternative ideas on this.
Bug appeared recently and I did not change anything about Spring. I don't think I installed anything new on PC also. Maybe it's random applications interfering with it, I don't know. It's annoying just because I have to ruin at least one game to notice it.