Strange behavoir when saving audio file

I record very long audio sessions and expect delays because of the very large file size. When I finish a 15 hour session, it can take 20 - 30 minutes to save. When I want to go to a specific location in the track, there are exceptionally long delays. This I understand and can accept.

If I save then cut the file to two hours, it still behaves as if I am working with the original 15 hours of audio. If I go to any location in this two hour track, there are the same delays as if I have the original file. I can save the audio then re-open it, the long delays are still there. Like having phantom pain after a limb has been severed, the software continues to believe that the original 15 hours are still there.

Is there some rebuild that can be done to get rid of the fragments?
I know that a database has to be rebuilt after many transactions so I wonder if some operation has be run to help ease this problem.

Thoughts ?

Has the project been saved? If it has, how much free space is there on the drive where it is saved. If it’s not been saved, how much free space is there on your C: drive (assuming that you have not changed the default location of Audacity’s temp folder).
Audacity projects can grow very large as they retain all audio data until the project is closed (so that “Undo” can work). On closing the project, the Undo history data is deleted.

I have 2 Tb of a 4 Tb drive free. It happens on more than one computer so I doubt that storage or CPU speed has much to do with it.

In my exploration, I see that a file is saved 2 - 3 times a minuter in the temp folder. This could add up to a thousand files in one session and I do one on Saturday and another on Sunday. 2000 small files, noteworthy or not? This is just an observation.

I am recording mostly voice and am doing this only for replay, no editing or saving any longer than it takes to replay once.

Audacity saves the audio data in small chunks (“block files”), each with an “AU” file extension. During recording, by default there should be one new “AU” file every 6 seconds or so.
Avoid having your file manager open while recording. With so many data files there can be a considerable slow down if Windows is trying to index them for display in the file manager.

Also, if you are running a third party anti-virus application, ensure that it ignores Audacity’s AU data files.

There don’t seem to be any problems with smaller files or those with lower bit/sample rate. Unfortunately, too low a bit rate then the file will not convert to an audio file. I guess I will just have to continue exploring.