Nimo2012

suggest you to check the task manager first to identify if the lagging is due to high CPU usage or Hard drive too busy. Most likely it is hard drive too busy.
Your config should be good enough to play 1080p video.

Nimo2012

the cpu usage is unbalanced between the 4 cores. this may not be causing audio lagging you encounter, you still need to rectify for performance improvement.

have you checcked the hard drive loading when you encountered the lagging? you may select I/O columns in task manager to check this.