Slowdowns in Firefox 4 Beta / RC when using ViewAbout 2.0

How many of you experience slowdowns when using ViewAbout 2.0? I’ve noticed that when there is high I/O activity, viewabout.js sometimes throws up a slow JavaScript dialog on startup. Recently, I’ve also noticed that the performance of Firefox 4 Beta / RC seems to slowdown significantly over time as one uses large numbers of tabs (e.g. more than 80) and one would have to restart Firefox. Or disable ViewAbout and the issue seems to go away.

I’ve also experienced lags when opening new windows through JavaScript links with the extension. Another ponder: How easy would it be to transit ViewAbout to being restart-less? There doesn’t seem to be a menu API in the latest Add-on SDK at the time of writing.

The relevant viewabout.js file is located here. Some of that code was submitted by a contributor some time back, and I’m not entirely sure what is causing the issue. Any ideas?

Edit: I’ve released the ViewAbout 2.0.1 hotfix to AMO to try and combat this issue. Thanks especially go out to harry for suggesting an alternative way of detecting about: URLs in the application.