This is typically caused by the AutoColor function being toggled on (Ctrl + Shft A).
Simply toggle it off using the same Shortcut.
AutoColor is constantly scrubbing the worksheet for cell content to format based on input type. When you insert a new column, the macro is "looking" at all 1,048,576 new rows.
Some users remap the Ctrl +Shft A Shortcut, as it's pretty easy to accidentally fat finger it on. To remap any Shortcut go to the TTS Turbo Options via Alt + S S