Possible optimisation trick?

[Russ Brown]

Apologies if this is old news to you highly experienced Python 
developers, I'm not intending to insult anyone by suggesting this. :)

But I just saw this on Planet Ubuntu:

http://juliank.wordpress.com/2008/04/29/python-speed-x-in-list-vs-x-in-set/

...and wondered if it might be of use in helping to improve bzr's 
performance?

I'm not particularly well versed in Python optimisation techniques so 
this was completely new to me. Again, apologies if it's well-known 
already and completely useless as a result. :)

-- 

Russ.