Very slow in edit mode

[home at quick-calcs.net]

I don't know if anyone has ever had this problem, but I've got one card which is incredibly slow when trying to edit it.

For example, moving a button takes over 10 seconds, aligning 4 fields takes almost 30 secs.  Even making a selection can take several seconds.

The card runs fine in run mode and also as a standalone.

All the other cards in the stack are fine.

The bad card has 10 datagrids each with 100 values each, but apart from that they all do similar things.

I'm not sure how to solve this, or even where to look, so any advice would be welcome.

Kev