Supercharge Zsh Startup

2020-01-03

Waylon Walker

💨 How Fast can it be

Quick side note: your zsh config is controled by your ~/.zshrc file. This file can source other files, load plugins, or run literally anything.

Time the initial time






        
time zsh -c exit

Move your ~/.zshrc config file.






        
mv ~/.zshrc ~/.zshrc-back

Time the fastest startup possible with nothing in your ~/.zshrc config file.






        
time zsh -c exit

Move your ~/.zshrc back






        
mv ~/.zshrc-back ~/.zshrc

🕵️‍♂️Profile your startup time

It is possible to profile your zsh startup time by adding zmodload zsh/zprof to the start of your ~/.zshrc file and zprof at the end. This was unsuccessfull for me. I ended up just backing up ~/.zshrc file, then deleting half of it to see where the hot spots were. I found that two places that were really hot for me. One I was inadvertantly setting git and npm settings everytime that didn't need to be set everytime. That was an easy 2s gain. Another easy 3s gain was removing oh-my-zsh.






        
# ~/.zshrc
zmodload zsh/zprof
...
..
.
zprof

😭But I really like oh-my-zsh

without all the bells and whistle that oh-my-zsh provided zsh became lightning fast to load, but incredibly boring. It was also very painful to manually type out everything that it autocompleted or aliased all the time. Next I headed down a path to get all of that functionality back without sacrificing load time.

Without oh-my-zsh, zsh became incredibly boring.

🔌 Plugin Managers

Photo by Steve Johnson on Unsplash

oh-my-zsh
zplugin
zgen

There are a number of plugin managers for zsh, I tried each of the ones listed above, but found that as I approached a nice setup that I liked the load time would creep up above the 2s mark each time. I would turn certain plugins on and off, try different plugin managers, before realizing that I had spent enough time on this problem and it was going to be time to settle on fast startup or functionality.

⚖ Finding Balance

Semi-lazy loading

Photo by Jeppe Hove Jensen on Unsplash

After struggling to get all of the features I wanted with a fast load time, I decided to only load what I needed upon startup. Next I created a simple alias that loads in zgen and all of the plugins I want. By doing this I get two main benefits. Obviously I get a faster starup time by loading less. I got my startup time down to about 0.25s.






        
# ~/.zshrc
p () {
zgen load zsh-users/zsh-autosuggestions
....
..
.
}

⚡ Fast Loading

I really like the fast startup time, because sometimes I am only loading up zsh to run a handful of commands that dont need much in the way of plugins

simple commands that need 💨 blazing start speed

any single easy to type command, these are my common commands that I will open a terminal in my editor and just need to run quick.

vim
git add . && git commit && git push
sh my_script.sh
make build
bake build
pytest
gatsby develop
npm i
npm update
pip install
ipython

The second benefit was that I can continue typing while plugins are loading.

>Prompt

After removing oh-my-zsh the first thing that I missed was the themes that it provided. I went through a number of them and the one that seemed to have the smallest effect on performance and everything I needed was starship. It's a really fast prompt written in rust. The biggest thing that I needed to have that other prompts were misssing was conda environments. I live much of my work life running python from various conda environments and it is crutial that I can see what environment I am in at all times.

![](https://images.waylonwalker.com/2020-01-04 12-36-31_Cortana.png)

💰 Bonus

I applied the same logic to neovim and achieved similar results. Again it just had too many plugins loading on startup for simple tasks. I ended up taking a shortcut and load any heavy plugins upon NerdTreeToggle. I dont really use NERDTree that much, but when I do its for more than just a quick edit.






        
# ~/.config/nvim/init.vim
Plug 'valloric/youcompleteme', {'do': './install.py', 'on': 'NERDTreeToggle'}