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bug#15294: 24.3.50; js2-mode parser is several times slower in lexical-b
bug#15294: 24.3.50; js2-mode parser is several times slower in lexical-binding mode
Fri, 06 Sep 2013 23:59:20 +0300
If I append -*- lexical-binding: t -*- to the first line of js2-mode.el
and eval the buffer, parsing a file takes several (3 to 4) times longer.
0. Install js2-mode, e.g. from GNU ELPA.
some local directory, open it in Emacs.
2. If it opens in some other mode than js2-mode, M-x js2-mode.
3. Don't touch the keys, wait until the file is parsed (the parsing gets
interrupted and rescheduled on input). When redisplay works again, we
can re-parse the file again and measure the time it takes.
4. eval-expression (js2-time (js2-reparse t)), wait until the message
area displays the amount of seconds the process took.
To measure the performance in interpreted mode, open js2-mode.el, M-x
eval-buffer and go through the above scenario (1-4).
To measure the performance in compiled mode, M-x byte-compile-file, then
(load "js2-mode.elc"), then go through the scenario.
lexical-binding | no | yes |
Interpreted | 1 sec | 4.26 sec |
Compiled | 0.63 sec | 1.76 sec |
In GNU Emacs 220.127.116.11 (x86_64-unknown-linux-gnu, GTK+ Version 3.6.4)
of 2013-09-06 on axl
Bzr revision: 114159 address@hidden
Windowing system distributor `The X.Org Foundation', version 11.0.11303000
System Description: Ubuntu 13.04