Today I Learned

Lazy-load NVM to speed up zsh initialization

UPDATE Once appending --no-use, ensure to source $NVM_DIR/.nvm.sh when actually needed. For example, yarn install will complain node: No such file or directory

I was curious as to why the zsh initialization was so slow. After some benchmarking .zshrc, I learned that oh-my-zsh and NVM were the main source of slow-down. For oh-my-zsh, I'm trying to see if I can avoid loading plugins that I rarely use to cut some time. However for nvm, simply passing `--no-use the following will make a big difference.

[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh" --no-use

Benchmarking with bash's buil-in time command...

Before --no-use:

❯ for i in $(seq 1 5); do /usr/bin/time zsh -i -c exit; done
        1.43 real         0.65 user         0.62 sys
        2.42 real         0.66 user         0.61 sys
        1.42 real         0.65 user         0.61 sys
        1.42 real         0.65 user         0.61 sys
        2.43 real         0.66 user         0.62 sys

After --no-use:

❯ for i in $(seq 1 5); do /usr/bin/time zsh -i -c exit; done
        0.48 real         0.26 user         0.17 sys
        0.46 real         0.25 user         0.16 sys
        0.46 real         0.25 user         0.16 sys
        0.46 real         0.26 user         0.16 sys
        0.49 real         0.27 user         0.17 sys

Sources:

https://github.com/creationix/nvm/issues/539 https://github.com/michaelmoussa/dotfiles/commit/8d67223aad5885ffc17e540b00e00478dd3c44d2 https://blog.jonlu.ca/posts/speeding-up-zsh