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Cleaning out my zsh: bye oh-my-zsh, bye zplug

· nixosdevops

My zsh startup had crept past half a second and I’d stopped noticing, the way you stop noticing a fan that’s always on. Then I actually timed it: ~660ms to get a prompt. On a machine that builds the whole OS from a flake, waiting two-thirds of a second for a shell is embarrassing. So I pulled it apart.

The culprit wasn’t my config. It was two layers of framework I was paying for and not using.

oh-my-zsh: eleven plugins, all redundant

oh-my-zsh was loading eleven plugins and a theme. Every one of them was already covered somewhere else: the theme by stylix (gruvbox is system-wide, OMZ wasn’t doing the colours), history search by atuin, the prompt by starship — which OMZ was also loading as a plugin, so it ran twice. The sudo plugin, the git aliases, the completion tweaks: all things Home Manager modules or my own config already do.

OMZ was pure overhead. Worse, its precmd hooks were quietly interfering with my own — I had visual command-boxes that only started rendering correctly after I removed it. Gone. The look didn’t change one pixel, because the look was never OMZ’s job.

zplug: 290ms to load a single plugin

The other passenger was zplug, a plugin manager loading exactly one plugin: github-copilot’s shell suggestions. ~290ms of startup to source one file.

The fix wasn’t a faster manager — it was no manager. On NixOS you don’t need a runtime plugin manager at all; you have the best one already, pinned and reproducible:

programs.zsh.plugins = [{
  name = "you-should-use";
  src = pkgs.fetchFromGitHub { /* pinned rev + hash */ };
}];

Load the source directly from a fetchFromGitHub and the whole “manager” concept evaporates. No defer logic, no clone-on-first-run, no lockfile that isn’t my flake.lock.

The errors that were hiding in the dark

Here’s the part I didn’t expect. zplug loaded that copilot plugin with defer:2 — lazily, after the prompt. Which meant the plugin’s startup error — gh copilot extension not found — was being swallowed every single time. The gh-copilot CLI isn’t installed here and isn’t wanted; my AI stack is Claude / Antigravity / Ollama, not Copilot. The moment I switched to native loading, the error jumped out at startup on every new shell.

Good. That’s the point of cleaning up: the mess you can see is the mess you can delete. The plugin and its two keybindings are gone, and that shaved another 60ms (~420ms → ~360ms).

Same story with my command-boxes — the > cmd and ✔ Command completed boxes that OMZ’s hooks had been suppressing. Once they actually rendered, they ate vertical space and added confirmation noise I never asked for. Defaulted them off; a toggle_boxes function brings them back per session if I want them.

The one real trap: compinit

Removing OMZ briefly made things worse — a 3.9s regression. The completion dump (compinit) was rebuilding from scratch on every shell, because ZDOTDIR was empty and the freshness check was globbing a path that didn’t exist. OMZ had been masking that with its own compinit handling.

The fix is the canonical one: a stable XDG cache location and compinit -C -d, which trusts the dump and rebuilds it at most once a day instead of doing the full security audit every prompt.

~660ms  → starting point (OMZ + zplug)
 ~3.9s  → mid-removal, compinit rebuilding every shell (yikes)
~420ms  → OMZ gone, compinit cached
~360ms  → copilot plugin gone, native loading

What I added back

Cleaning out isn’t the same as going minimal. With the frameworks gone I had budget to spend on things I actually use, all declarative in one zsh-enhancements.nix:

  • zsh-abbr — expand-on-space abbreviations for the commands my fingers type on autopilot: git, nix, just, claude.
  • dirHashes — cd ~nixos, ~src, ~dl.
  • Esc-Esc to prepend sudo to the last command (replacing the OMZ plugin).
  • fzf pickers — fj (just recipe), fgb (git branch), fh (ssh host).
  • wtf — pipe the last failed command to Claude and ask what went wrong.

The lesson I keep relearning: a framework is a default you’ve stopped questioning. atuin, starship and stylix earn their place every shell. oh-my-zsh and zplug were just where my config used to live before I knew better. 360ms and no errors at login — I’ll take it.

Written by Olaf Krasicki-Freund · LinkedIn · GitHub