Re: Why it is necessary to compile el files?

[David Hansen]

On Sat, 29 Sep 2007 11:48:05 +0900 Ke Lu wrote:

> Why it is necessary to compile el files?
>
> I can't fell it become faster after compile el files.
> I often install emacs package without make and just
> add load script which like following
> (add-to-list 'load-path "path-of-package")
> (require 'xxx)
>
> I think it makes things easy.
>
> I want to know Why it is necessary to compile el files?
> If it makes the speed up,How can I feel it?

It's not necessary, but it definitively speeds up things (especially
when macros are involved):

,----[ tst.el ]
| (eval-when-compile (require 'cl))
| (dotimes (i 1000000)
|   (let ((foo '()))
|     (push 'bar foo)
|     (pop foo)))
`----

$ time emacs -Q -batch -l tst.el

real    0m14.360s
user    0m14.109s
sys     0m0.124s

$ time emacs -Q -batch -l tst.elc

real    0m0.948s
user    0m0.936s
sys     0m0.008s

But this is a rather drastic example.

David