mrkaplan post 2 years ago but didn't have solution so i'll give another try. i'm having the same problem here.
I have dual monitors . today i tried maximized space on main monitor by placing command line on 2nd screen . Strangely when i do that , autocad is slowed down . any command has a lag of about a second . i usually have adcenter and toolpalettes on 2nd monitor with no problem . any idea why this happens ?