Timeline of the cat crash
Usually it just takes forever, especially waiting for bits (on Firefox); but I've tried now with Chromium and it crashed completely ("whoops"): 23.0.1271.95 Built from source for Fedora release 17 (Beefy Miracle) (169798).
I don't know how to attach useful data, I made a screenshot of the timeline. U used "Cat" ([[wikidata:Q146]]) as example, the problem usually happens with bigger entries – I think –.
Version: unspecified
Severity: major
URL: https://www.wikidata.org/wiki/Q146
Attached: