>>> I've now come up with the code as shown in the attachment.  It
>>> works fine, however, I would like to not have empty lines; in
>>> other words, invisible text should not take any space in the
>>> buffer.  Does Emacs supports such a `compressed invisibility'?
>>
>> 
>> Make the newline invisible.
> 
> Thanks!  This perhaps deserves a notice in the documentation.

I've now tried the code with my real-world table (containing
approx. 420000 lines):

  git://repo.or.cz/srv/git/wortliste.git

and I found out that it is, alas, unusable.  It starts with about 1000
replacements per second on my GNU/Linux box (using simply `-' as the
regexp), but soon the speed decreases: After approx. 10000
replacements it only can handle 100 replacements per second -- the
attached code now contains a small counter to show the progress.  If
you comment out the call to `make-overlay', the code really flies...

Am I doing something wrong?


    Werner