X61 2006 bring to life

Core2Duo 2GB and 160SSD upgrade I was sure Intel iGPU will handle by hardware x264 but forgot to check - it's that old... I use only for presentation LibreOffice on Linux Mint. Sadly up to 720p in dual screen mode during presentation just a little laggy. I have 1024x768 DLP by VGA and slides visual on build in LCD.

Maybe it's a little to slow for these? Video is coded 24fps 9000 kbs mpeg2 ~1024x560p and CPU hits ~70% utilization.

Maybe a little advice about codec?