Earlier quoted context omitted.
Interesting on chrome Version 24.0.1312.57 the tab crashes when i try to view the tweet but not here. Can someone explain what is happening and why the tweet is affecting the tab and this post does not? In the end both just render unicode characters. And it looks like only Firefox is able to display it correctly on OSX 10.8.
Chrome uses OS X's CoreText for rendering the tab titles, but uses its own text rendering engine for the site body. CoreText is the one that crashes on that unicode.
Meanwhile on Chromium 26.0.1384.0 (build 176849) on OS X Lion everything is fine for me. The titlebar is (appropriately for the typography) messed up, but there are no tab loading issues, cpu/memory spikes, or screen corruption. The closest thing to an issue I see is that it makes using Witch's window switch dialogue a bit ugly. Contrary to the thread on jwz's journal YoruFukurou 2.77 doesn't crash or misbehave for me viewing that tweet, but behind the scenes fontd uses up a decent chunk of cpu for several seconds. Perhaps Mountain Lion has more severe bugs in CoreText?