Oh, sorry forgot to indicate. Both Server (NAV Server Side) and POS Unit (NAV + LS Client Side) has a 8GB of RAM.
But the issue was - When Dynamics NAV Server consumes memory from 1GB to 5GB -Their LS Retail will be slow on processing
Restarting the Server will make it normal.
But the Slowness Issue will re-occur after several days.
Thank You,
Elrey Resultan