Zsh Startup Performance Rules

This rule applies to files matching the patterns above.

# Zsh Startup Performance Rules

## Rule
Zsh interactive shell startup MUST complete in under 200ms. Heavy tools (nvm, pyenv, conda, kubectl completions) MUST be lazy-loaded.

## Performance Budget
| Component | Max Time |
|-----------|----------|
| Total startup | < 200ms |
| compinit | < 30ms |
| Oh My Zsh plugins (combined) | < 100ms |
| Single plugin | < 20ms |
| Prompt init | < 20ms |

## Measurement
```bash
# Measure total startup time
time zsh -i -c exit

# Profile with zprof
# Add to TOP of .zshrc:
zmodload zsh/zprof
# Add to BOTTOM of .zshrc:
zprof
```

## Lazy-Loading Pattern
```bash
# Good: nvm loaded on first use (saves ~500ms)
lazy_load_nvm() {
  unset -f nvm node npm npx
  export NVM_DIR="$HOME/.nvm"
  [[ -s "$NVM_DIR/nvm.sh" ]] && source "$NVM_DIR/nvm.sh"
}
nvm() { lazy_load_nvm; nvm "$@"; }
node() { lazy_load_nvm; node "$@"; }
npm() { lazy_load_nvm; npm "$@"; }
npx() { lazy_load_nvm; npx "$@"; }

# Bad: loaded eagerly (adds 500ms+)
export NVM_DIR="$HOME/.nvm"
source "$NVM_DIR/nvm.sh"
```

## Plugin Limits
```bash
# Good: 5-8 essential plugins
plugins=(git z fzf zsh-autosuggestions zsh-syntax-highlighting)

# Bad: 15+ plugins
plugins=(git docker kubectl aws npm yarn python ruby rails
         z fzf zsh-autosuggestions zsh-syntax-highlighting
         colored-man-pages web-search encode64)
```

## Compinit Caching
```bash
# Good: rebuild once per day
autoload -Uz compinit
if [[ -n ~/.zcompdump(#qN.mh+24) ]]; then
  compinit
else
  compinit -C
fi

# Bad: rebuild every startup
autoload -Uz compinit && compinit
```

## Good
```bash
# Profile output shows < 200ms total
# num  calls   time            self            name
# 1)   1       15.20   45.00%  15.20   45.00%  compinit
# 2)   1        8.30   24.56%   8.30   24.56%  _zsh_highlight
```

## Bad
```bash
# Profile output shows > 500ms
# num  calls   time            self            name
# 1)   1      520.00   65.00%  520.00  65.00%  nvm_auto
# 2)   1      180.00   22.50%  180.00  22.50%  compinit
```