Oh it is not normal.
You should start looking into what is causing it.
Start by doing ‘stat unit’ and see if you are CPU or GPU bound. Then go from there. Use the other stat commands.
For more detailed GPU detail you can dump stats into the logfile by pressing Ctrl+Shift+comma.
For more CPU stats run the commands ‘stat startfile’ then after a few seconds ‘stat stopfile’ and then you can open this up in the ‘Session Frontend’ app provided with the engine.