(from http://bugs.debian.org/309070)

When trying to merge two big po files (dpkg's po) I found that the
application is really slow when trying to edit either of the merged
files. The files are both over 160KB.

...

having edited my girl friend's diploma thesis recently -- 5200 lines,
283k -- I want to affirm the submitters findings.  Editing is slow,
sometimes even scrolling is slow.  I estimate meld is roughly a half to
a full second behind when I type, that's easily a full word.  My box has
a 1800+ Athlon CPU, I guess that should be enough to work flawlessly...