Fixing my performance problems on Emacs

Oct 19, 2016 min read

As you might know, I’ve had several performance problems on Emacs with a large project, that made me explore other editors.

At some point I missed a lot of things from Emacs, I have everything nicely configured there, and decided to spend some time checking out my issues and trying to fix them.

Most of my problems are due to projectile, I realised an option wasn’t configured the way I thought!

projectile-indexing-method was alien when I thought It was native. According to projectile:

There are two indexing methods - native and alien.

The native method is implemented in Emacs Lisp (therefore it is native to Emacs). It’s advantage is that is portable and will work everywhere that Emacs does. It’s disadvantage is that is a bit slow (especially for large projects). Generally it’s a good idea to pair the native indexing method with caching.

The alien indexing method uses external tools (e.g. git, find, etc) to speed up the indexing process. The disadvantage of this method is that it’s not well supported on Windows systems.

By default alien indexing is the default on all operating systems, except Windows.

That meant I had to enable the projectile cache manually, as I did.

(setq projectile-enable-caching t)

Regarding garbage collection, It seemed someone did a much better research than me, so I got some of his tips to improve my configuration. Now the threshold is changed when opening the minibuffer (for helm mostly).

-      (setq gc-cons-threshold 100000000)
+      (defun my-minibuffer-setup-hook ()
+       (setq gc-cons-threshold most-positive-fixnum))
+      (defun my-minibuffer-exit-hook ()
+       (setq gc-cons-threshold 800000))
+      (add-hook 'minibuffer-setup-hook #'my-minibuffer-setup-hook)
+      (add-hook 'minibuffer-exit-hook #'my-minibuffer-exit-hook)

Today was my first day profiling Emacs, It was as easy as using the profiler-start, profiler-stop and profiler-report command (which opens a buffer with the report data, TAB to open the details of each line on the report). You can use profiler-reset in case you want to check if your new configuration works better, having a new report.

In the meantime, I’ve added some cool features I was missing from other editors, such as Dumb Jump, to jump to definitions in other files, or quick check where a method/class is defined.

I also improved my ctags options to exclude vendor directories and add support for coffeescript.

I’m using Neotree with the command neotree-projectile-action to show the project directory tree when necessary.

Another nice package I’m using now is Anler’s centered-window-mode, to center the view if we have only one window opened.

Everything can be seen in my Emacs configuration on Github.