User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4 Build Identifier: Changing the spelling language in Thunderbird and Firefox is rather slow and could benefit from a performance improvement. This is a functionality used quite often if you are working in a dual/multi-language environment. Reproducible: Always

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4 I pasted the contents of a entire web page to this bug and changed the language to Dutch and it takes one or two seconds before the context menu disappears. Which seems indeed rather slow. CPU is ADM Athlon 2000+.

Is it slow on trunk as well?

(In reply to comment #2) > Is it slow on trunk as well? > Yeah, also on trunk.

if it is still slow then this should be confirmed

I don't observe significant lag (0.25-0.5 seconds at most) on an average Celeron laptop after pasting a long text into the comments field of a bug, and switching from en-US to fr-FR and back. (text is http://ebooks.adelaide.edu.au/j/joyce/james/j8d/chapter15.html) I do notice that the spell checker is going through the text and underlining misspelled words. The large number of misspellings when you switch between languages was probably the original cause of the delay. There is a workaround if you have a very slow computer: decrease the number of max-misspellings from 500 to 100. http://kb.mozillazine.org/Extensions.spellcheck.inline.max-misspellings For most users, this was fixed by Hunspell or Bug 341420. Resolving WFM.

I can confirm that this bug is no longer present in Firefox 3.0.11 and Thunderbird 3b2. The only app. where the language change is still slow is Thunderbird 2(.0.0.21). I don't know whether this bug really relates to Bug 341420 as the other bug was fixed quite some time before I reported this one. The difference in application behaviour seems to be that now the spell checking takes place after the language change while it probably was done during the language change previously. As I am not deeper involved, this is just the observation from an application user.

OK, thanks for the report. Resolving as fixed.