> So I restarted 
> the download and the program is now running for 10 hours 
> and is still updating yesterdays files. 

You should have used 'CONTINUE an interrupted mirror', 
not 'Update' (with fast lines and small html files, 
updating is as long as downloading)

> You could create a 
> stronger autosave, which would save the whole project 
> detail and would resume from the last save.

The continue mode should be much faster (note: if you 
interrupt the current update, first delete hts-cache/new.* 
files to discard the previous cache, and leave old.* 
entries)