Closed
Description
When printing lots of lines, the performances of nrepl are really bad (emacs hang out for a long time, depending how long is the nrepl buffer). This seems to come from nrepl-show-maximum-output:
(dotimes (i 1000)
(with-current-buffer nrepl-nrepl-buffer
(insert-before-markers "foo\n")
(nrepl-show-maximum-output)))Takes 0.7827s to run on a clean buffer (that has just been C-c C-o'd), while
(dotimes (i 1000)
(with-current-buffer nrepl-nrepl-buffer
(insert-before-markers "foo\n")))only takes 0.0169s.
The more the nrepl buffer is long, the more time it will take. For example, with a ~13k lines buffer, it takes around 7s while only 0.018s without nrepl-show-maximum-output.
This affects the performance of clojure codes that prints lots of stuff (eg. (dotimes [i 1000] (println "foo"))) to the point that you might have to kill emacs because it does not respond anymore.