Hm, that definitely should not be the case.

A few ideas that could be related:
1. Do you have Gears enabled? (I don't think it's supported on 3.5 yet, but just checking.)
2. Does this happen if you search only for incomplete tasks? For example, instead of selecting smart list Stuff To Do, search for list:"Stuff To Do" status:incomplete. Let me know if that performs any more faster.
3. Does it happen if you start Firefox in safe mode? (This will disable some settings and all extensions that may be conflicting.)
4. Does this happen if you log out and back in?
5. Does it happen if you clear your cache? (Tools | Clear Recent History, choose "Everything" and check "Cache" only (checking any others may result in the loss of other desired data).

Hope this helps! Let me know how it goes!

On my Vista Business/Firefox 3.5 configuration RTM is slower and less responsive that on Chrome or previous Firefox versions. Any suggestions?

My apologizes. I somehow overlooked this post before posting mine just now. Seems we're experiencing the same issue, rockivist.

Upon updating to Firefox 3.5.1, the problem persists but is much more tolerable. Any updates on your situation rockivist?

I'd be curious if anyone experiencing any problems could answer the questions I posted to rockivist above. (dorian, in particular I wonder if Gears might be the difference between Chrome and Firefox for you.)

1. Do you have Gears enabled? (I don't think it's supported on 3.5 yet, but just checking.)
No
2. Does this happen if you search only for incomplete tasks? For example, instead of selecting smart list Stuff To Do, search for list:"Stuff To Do" status:incomplete. Let me know if that performs any more faster.
Yes
3. Does it happen if you start Firefox in safe mode? (This will disable some settings and all extensions that may be conflicting.)
Yes, but seemed to be slightly better
4. Does this happen if you log out and back in?
Yes
5. Does it happen if you clear your cache? (Tools | Clear Recent History, choose "Everything" and check "Cache" only (checking any others may result in the loss of other desired data).
Yes

1. Do you have Gears enabled? (I don't think it's supported on 3.5 yet, but just checking.)
No
2. Does this happen if you search only for incomplete tasks? For example, instead of selecting smart list Stuff To Do, search for list:"Stuff To Do" status:incomplete. Let me know if that performs any more faster.
Yes, but it didn't last as long.
3. Does it happen if you start Firefox in safe mode? (This will disable some settings and all extensions that may be conflicting.)
No. I can quickly dump a list of extensions if you want.
4. Does this happen if you log out and back in?
Yes
5. Does it happen if you clear your cache? (Tools | Clear Recent History, choose "Everything" and check "Cache" only (checking any others may result in the loss of other desired data).
Yes

jrf9g, viewer: Thanks for answering the questions.

jrf9g: It sounds like you're running into a performance bug we know about. Would it be possible to submit a Tasks & Lists issue report via our support system so we could discuss some details?

viewer, if you're experiencing a problem that's resolved in safe mode, I'd suggest disabling all extensions and seeing if it works then. It could be a conflicting extension...

But it could be a corrupt setting or something too. If it's not an extension, you could also create a new Firefox profile and narrow down the problem there.

Thanks!

It is indeed a conflicting extension. For anyone else experiencing this, disable the extension LongURL Mobile Expander (https://addons.mozilla.org/en-US/firefox/addon/8636).

Also, if you continue to have problems after trying my suggestions above, I'd be curious to know which OS you're using.

I was having the same issues and can confirm that disabling LongURL expander worked for me also. Thanks @andrewski and @viewer