I’ve been using Robby Russell’s oh-my-zsh for as long as I remember. It’s familiar to me, and it looks nice. I like the agnoster theme. It’s one of the first things I install on every computer.
One of the costs of using Oh-my-zsh is that the startup times are slow. That’s what everyone says.
So I accepted that fate. Recently, I’ve been getting more and more frustrated by the slow startup times, so I turned to the internet to see what I can do to make it faster.
Step 1: Benchmarking Current Performance
First, I figured out how long it took to start a new shell session. The results were not pretty:
$ /usr/bin/time zsh -i -c exit 3.07 real 1.58 user 1.27 sys
Results: 3.07 seconds. That’s the time it takes for a new shell to open. Not Good.
Step 2: Figure Out What Was Slow
The next step is to determine what causes the slowness.
Running zsh with the -xv flag gives us a read out on what’s going on.
$ zsh -xv
However, after some thought, I realize I don’t use these commands all too often.
Step 3: Removing the Infrequently Used
The key insight I have at this point is that I don’t need nvm_ and rvm all that often. As it turns out, only when I’m going between different projects. As a result, I decided to not load them on every shell load, but only do it as needed.
In my .zshrc file, I created two aliases that help me load nvm and rvm.
alias loadrvm='[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm"' alias loadnvm='[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"'
After that, I just removed the default configurations for nvm and rvm.
Here is the result:
$ /usr/bin/time zsh -i -c exit 0.28 real 0.13 user 0.11 sys
After the two minor tweaks, I got zsh to start in just 280 ms:
I say that’s a win for a few minutes of work. And I get to keep the configuration I’m familiar with!
Checkout my dotfiles here: