scalc slow over ssh-forwarded X11

I’ve been using scalc over the network (ssh-forwarded X11) for a long time; I noticed that in recent versions, whenever I press Ctrl-C to copy a cell, the UI becomes quite slow and unresponsive.

I believe the culprit is the “animation” effect of the dashed border around the cell that I select.

I’m using and in earlier versions the effect wasn’t as noticeable as it now is.

Is it a known problem or is there a way to disable the animation?

Hit the Escape key.