mplayer lagging my computer

[days of wild]

hi, new to forum and UMS , i have got it working great now and im really pleased with this app, thanks. I was a PMS user but that stopped working for an unknown reason i still cant figure out. The only snag i have after working out that mplayer.exe runs when i load up UMS and it makes my pc lag badly... turn it off in task manager all is good, pc acts good and UMS streams great too...any ideas please for a noob!