When the user drags the image screenshot over the panel the spectacle's cpu usage go crazy... This makes difficult some times for the user to directly hover with that image an app e.g. internet, mail etc. in order to attach it in that app The problem was first noticed with Latte Dock but it is confirmed that it also occurs with the original plasma panels... confirmed also with plasma: 5.9.3 Steps to reproduce: the user drags the screenshot image and continuously hovers a panel with it....
must have been fixed from: https://bugs.kde.org/show_bug.cgi?id=380270