Quote - More of a freeze.

One potential cure that I've seen mentioned is to lower the number of undos.
What's happening, while it appears to be a freeze, it isn't, Poser is saving the figure's state in case you undo the deletion.
If you have a high number of undos set, Poser has to keep track of them, which can be a lot of work and so cause a significant unresponsive period.