Open Source Emacs Configuration Improvements

In retrospect I’m not totally sure why I released my emacs configuration to the world. I find tweaking Emacs Lisp to be soothing, and in 2020 these kinds of projects are particularly welcome. I’ve always thought about making it public: I feel like I get a lot out of Emacs, and I’m super aware that it’s very hard for people who haven’t been using Emacs forever to get a comparable experience.¹

I also really had no idea of what to expect, and while it’s still really recent, I’ve noticed a few things which are worth remarking:

• Making your code usable for other people really does make it easy for people to find bugs. While it’s likely that there are bugs that people never noticed, I found a few things very quickly:

  • Someone reported higher than expected CPU use, and I discovered that there were a number of functions that ran regularly in timers, and I was able to quickly tune some knobs in order to reduce average CPU use by a lot. This is likely to be great both for the user in question, but also because it’ll help battery life.
  • The config includes a git submodule (!) with the contents of all third-party packages, mostly to reduce friction for people getting started. Downloading all of the packages fresh from the archive would take a few minutes, and the git clone is just faster. I realized, when someone ran into some problems when running with emacs 28 (e.g. the development/mainline build,) that the byte-compilation formats were different, which made the emacs27 files not work on emacs28. I pushed a second branch.

  More than anything the experience of getting bug reports and feedback has been great. It both makes it possible to focus time because the impact of the work is really clear, and it also makes it clear to me that I’ve accumulated some actually decent Emacs Lisp skills, without really noticing it.²

• I was inspired to make a few structural improvements.

  • For a long time, including after the initial release, I had a “settings” file, and a “local functions” file that held code that I’d written or coppied from one place or another, and I finally divided them all into packages named tychoish-<thing>.el which allowed me to put all or most of the configuration into use-package forms, which is more consistent and also helps startup time a bit, and makes the directory structure a bit easier.
  • I also cleaned up a bunch of local snippets that I’d been carrying around, which wasn’t hurting anything but is a bit more clear in the present form.

• I believe that I’ve hit the limit, with regards to startup speed. I’d really like to get a GUI emacs instance to start (with no buffers) in less than a second, but it doesn’t seem super plausible. I got really close. At this point there are two factors that constrain:

  • Raw CPU speed. I have two computers, and the machine with the newer CPU is consistently 25% faster than the slow computer.
  • While the default configuration doesn’t do this, my personal configuration sets a font (this is reasonable,) but seems that the time to do this is sometimes observable, and proportional to the number of fonts you have installed on the system.³
  • Dependencies during the early load. I was able to save about 10% time by moving a function between package to reduce the packages that startup code depended upon. There’s just a limit to how much you can clean up here.

  Having said that, these things can drift pretty easily. I’ve added some helper macros with-timer and with-slow-op-timer that I can use to report the timing of operations during startup to make sure that things don’t slow down.

  Interestingly, I’ve experimented with byte-compiling my local configuration and I haven’t really noticed much of a speedup at this scale, so for ease I’ve been leaving my own lisp directory unbytecompiled.

• With everything in order, there’s not much to edit! I guess I’ll have other things to work on, but I have made a few improvements, generally:

  • Using the alert package for desktop notification, which allowed me to delete a legacy package I’ve been using. Deleting code is awesome.
  • I finally figured out how to really take advantage of projectile, which is now configured correctly, and has been a lot of help in my day-to-day work.
  • I’ve started using ERC more, and only really using my irssi (in screen) session as a fallback. My IRC/IM setup is a bit beyond the scope of this post but ERC has been a bit fussy to use on machines with intermittent connections, but I think I’ve been able to tweak that pretty well and have an experience that’s quite good.

It’s been interesting! And I’m looking forward to continuing to do this!