When I draw something, even just a line, the entire program lags and takes one second before I can do anything. Really annoying!
This is a bugtracker, not a helpdesk service. I recommend that you repost your problem on the forums, add the information in help->system information and give a bit more information about what kind of lag you are experiencing. People will be able to give much better help. The forums are here: https://forum.kde.org/viewforum.php?f=136 You can also try going into settings->display and set openGL to use ANGLE or to disable it alltogether. I will close this bugreport now, because even if this was a bug, there's too little information to do anything. I really recommend you go to the forums instead.