OpenRA

Online game? Just playing against AI? If it's online then it may be nothing to do with your own machine. If you are playing against the computer... the only thing I can think of was maybe your PC had background tasks that slowed it down... I don't but in game skirmish after 30 minutes, my game lag

Hi, I the last version release. My game after 30 minute begin lag.

I has a very good config computer

Windows 7 64 bit
GTX 480
I5-3570 3,40 GHz
JAVA version 8 51