On Mac, Slicer hangs for a while but doesn't crash.
Tracing through the events, the fiducials are removed from the list one by one, each removal triggering a markup removed event. That triggers updates in the 3d and 2d representations as well as updates to the GUI. I'm looking at batching that better so that only one update will need to be done (like how removing all markups is quick).

Could you attach a stack trace/error log for the crash on linux or windows?

I've sped up deleting fiducials with this commit:
https://github.com/naucoin/Slicer/commit/1927de616b40102dde9481e34cb384a57ae457b9
Rebuilding on linux to see if I can reproduce the crash and see if this fixes it.

Hi Nicole, thanks for looking into this.

What actually happens (Linux) is that Slicer becomes unresponsive and the windows gets white. So when I try to close it Ubuntu tells me it's unresponsive. The error log seems normal, but I can paste it here if you want.

I just tried today's nightly on Linux and it took a while to delete my 100 fiducials, but at least it didn't crash. Is there some other way to keep speeding it up? Maybe disabling some events? We don't need many functionalities of the Markups for this project, and we only use the 2D views.

Good to know, it was taking about 2 minutes to delete 100 fiducials on my Mac, but I let it run to time it, not trying to close it or interact with it. I didn't push that commit to the nightly yet as I wasn't sure if anything else was needed, so I'll do that now and the next nightly should show a significant speed up:
https://github.com/Slicer/Slicer/pull/557

I'll try again on Monday and let you know what happens.

Merged as of svn 25253:
http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=25253

It works perfectly.

Thanks Nicole!

Thanks for confirming!