Emacs Slow Startup

How to fix it

Try these in order — the most common fix is first.

1. 1. Find what is slow

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   1. Run M-x emacs-init-time
   2. Profile with M-x profiler-start before loading init, or use the benchmark-init package
   3. Remove or defer the biggest offenders
   Did this fix it? Yes No

2. 2. Defer package loading

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   1. With use-package, add :defer t or :commands
   2. Use autoload and eval-after-load instead of require
   3. Move heavy setup into hooks that fire on first use
   Did this fix it? Yes No

3. 3. Run Emacs as a daemon

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   1. Start with emacs --daemon
   2. Open files with emacsclient -c or emacsclient -t
   3. The init cost is paid once per login
   Did this fix it? Yes No

4. 4. Tame native compilation

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   1. Set native-comp-async-report-warnings-errors to nil
   2. Let the first launch finish compiling; later launches are faster
   3. If memory is a problem, test with native compilation disabled
   Did this fix it? Yes No

Symptoms

Seconds pass before the first window is usable, the *Messages* buffer shows long load times, or the CPU spikes right after launch.

Why it happens

• Packages loaded eagerly with require instead of being deferred
• Native compilation of packages running in the background after launch
• A very large init file or many customization files
• Many packages loaded at startup on slow disks or Windows

This guide also covers

• emacs slow startup
• why is emacs so slow to start
• emacs startup time

The same problem in other apps

All slow, laggy or resource-hungry guides →

• Why Is Neovim So Slow? (Startup Lag and Large Files) (Neovim)
• Why Is Vim So Slow? (Large Files & Long Lines) (Vim)
• IntelliJ IDEA High Memory Usage (JetBrains IntelliJ)
• Obsidian Mobile Slow to Open on iPhone and Android (Obsidian)

Other GNU Emacs errors

• Emacs Failed to Verify Signature (ELPA Package Install Error)
• Emacs Native Compilation Warnings Popping Up
• Emacs Slow or Freezing With Large Files
• Emacs Eglot / LSP Not Working
• Emacs macOS Operation Not Permitted (Documents, Desktop, iCloud)
• Doom Emacs Errors After Update or doom sync
• Emacs package-install Fails (Package Not Found or Archive Error)