Minecraft lag on strong computer?

So i know i already asked about minecraft but its really annoying me that i'm getting what seems like lag from a slow internet connection when i'm playing offline in single player what's the deal
i'm seeing [00:10:31 INFO]: Client> [00:10:31] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 6398ms behind, skipping 127 tick(s)
and i'm not running server Jar just the minecraft.exe from the website Very annoying
i have ran MC with fancy graphics and far distance before with 100 fps