Audacity works, even for FLAC to MP3. Great. But, sometimes it takes more than 2 ours to change 4 minutes music from Flac to MP3. Is this normal, or do I have to change a setting somewhere?
Have tried several things, can’t find it.

Windows XP? Vista? MAC? Linux?..
Audacity version?

Your computer speed?
Where are your files stored?
Do you save the (empty) project before you start, or do you let it in audacity_temp? Where is it? (Don’t you have there trash from hundered crashes from before?)
Do you close audacity after every other or tenth conversion?

Windows XP Audacity Version 1.2.6

Yes, but maybe I had some tracks converted together, I don’t know.
I’ve just tried to convert a track, it seems to work pretty nice today.
May be I have been to enthousiastic and had things going on at the same time, I don’t know.
Does the converting take more time than the actual lenght of the track?

Try upgrading to Audacity 1.3.4 or above.

Also, working on an external drive can slow things down a lot. Try working on the internal drive, then after a successful export, copy or move the files to the external drive.

Avoid having other cpu or disk intensive processes running at the same time (such as Windows update, or virus scanning)

That’s helps a lot, I was working with a large calculation program, e-mail program and playing music at the same time. When stopped, Audacity works fine. Thanks a lot.