I have that sometimes, when I draw and it's really annoying me: When I have finished drawing a line and want to reposition the pen or select a different tool, etc., nothing happens for about 2 to 3 seconds, every time after I have drawn a line (or have colored something out). :( (Hopefully I'm not too stupid to write a comment like that because I've never done it before..)
Hi Charlotte, I'm sorry, but this is very likely a problem with your system, and not with Krita. This sounds like it might be better to ask other Krita users for advice, instead of filing a bug report: our most active community forum is https://krita-artists.org.