[orca-list] Thunderbird has improved but I have one doubt

[Krishnakant mane <krmane gmail com>]

Hello all,
I wish to ask this question to all the thunderbird users.
Today I again set up imap for google on thunderbird.
I am kind of happy that some thing are better now that I have reduced the size of my inbox.
I find that when I use up and down arrow for selecting an email, I can just press f6 key to read it.
But very often, Orca starts responding slowly when I navigate through the list of emailsm while some times it 
is very smappy.
Why would this be?

Happy hacking.
Krishnakant.