Slow script problem Rated 5 out of 5 stars

I have been using this extension for years but lately I am having problem when opening new tabs:
A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete.
...treestyletab@piro.sakura.ne.jp/modules/utils.js:813"

I have stopped using the Tree Style Tab but I am lost. Please look into the problem.

This review is for a previous version of the add-on (0.10.2010051201).