Subj : JS spead in UI thread?
To   : netscape.public.mozilla.jseng
From : Peter Wilson
Date : Sun Feb 20 2005 10:57 am

In Firefox, I am writing a JS tokenizer using repeated regexp calls. The 
original version took twelve seconds to tokenize a 14k file. Given this 
pathetic speed I almost gave up.

Just to see how threading worked, I tried executing the same code in a 
separate thread. The code now executes in less than 0.5 seconds.

What causes the huge slowdown on the main UI thread?

.