WhoKnewKnows , 03-30-2022, 09:31 PM
Try opening Tools>Design Rule checker
When the dialog appears, select Rules to check in the left pane.
In the right pane, experiment with unchecking various rules in the online checkbox column. Maybe uncheck all check boxes in the online column and see if things get easier. In Altium, when there's a list of check boxes, sometimes you can right click in the area and select uncheck all and or check all. Look for such an option to help speed up checking and unchecking.
Perhaps after you uncheck all online rules, select OK to close the dialog box and get back to your PCB design. See if the sluggishness has gone away. If so, now you have to figure out which rule, or combination of rules caused the problem. Good luck