Dmx output slowing down

I was running 1.1.1 in nano mode on a HP touch PC with windows 7 when Incurred this problem

Output would begin to slow down over 20 minutes. logging off and on would fix the issue only to slow down again over the next 20mins

we had a superwidget hog 3 playback and program wings attached
was a small rig of just 2 technobeams 4 mac 101s and 26 generic RGB LEDs any ideas on what is causing this?

I had used the same computer on a show a month ago and didnt have this issue

Cheers

Steve