performance - How can I make Emacs start-up faster?

Question

I use Emacs v. 22 (the console version, either remotely with PuTTY or locally with Konsole) as my primary text editor on Linux. It takes a while to load up each time I start it though, probably almost a second, although I never timed it. I tend to open and close Emacs a lot, because I'm more comfortable using the Bash command-line for file/directory manipulation and compiling.

How can I speed up the start-up time?

Answer 1

Others have covered using gnuserve and emacsclient, and I'd suggest compiling within emacs (being able to jump to compilation errors is a win).

But, specifically speeding up the .emacs can be done by:

1. Byte compiling the .emacs file, which you can do automatically by using this snippet of code

2. Replacing as many of the (require 'package) statements with autoloaded functionality. This will delay loading of lisp until it's actually required. Using this technique allowed me to speed up my startup from >6 seconds to <1. This takes a little bit of work because not all libraries come properly marked autoload.

3. Removing code/functionality you no longer use.

4. Try running emacs with the option --no-site-file to avoid loading unnecessary packages in the site installation site-start.el.

5. If you are really serious, you can roll your own emacs with your favorite functionality already loaded. This, of course, means it's more involved to make changes to what you have in your .emacs because it's a part of the binary. Follow the link for information on how to use dump-emacs.

6. Buy a faster computer and/or faster disk.

How to determine what your .emacs loads

Now, how do you find out what your .emacs loads? With the goal to remove the functionality, or to delay it? Check your *Messages* buffer, which contains lines like:

Loading /home/tjackson/.emacs.tjackson.el (source)...
Loading /home/tjackson/installed/emacs/lisp/loaddefs.el (source)...done
Loading /user/tjackson/.elisp/source/loaddefs.el (source)...done
Loading autorevert...done
Loading /home/tjackson/.emacs.tjackson.el (source)...done

If you'll notice, the Loading statements can nest: the first .emacs.tjackson.el ends with ... and the last line shows the .emacs.tjackson.el load is ...done. All those other files are loaded from inside my .emacs.tjackson.el file. All the other loads are atomic.

Note: If you have a large .emacs, it's possible that the *Messages* buffer will lose some of the messages because it only keeps a fixed amount of information. You can add this setting early on to your .emacs to keep all the messages around:

(setq message-log-max t)

Note: It the 'load command will suppress the messages if its fourth argument nomessage is non-nil, so remove any such invocations (or, advise 'load and force the fourth argument to be nil).