Analyze Neovim Performance

Profile Neovim startup time, identify bottlenecks, and provide actionable optimization recommendations.

Task

Run startup profiling, analyze results, identify slow plugins and configurations, and suggest specific optimizations to improve performance.

Workflow

1. Check Prerequisites

Verify Neovim is available:

which nvim nvim --version

If not found, inform user and exit.

2. Ask User Preferences

Use AskUserQuestion to determine analysis scope:

Question: "What level of analysis do you want?" Options:

• "Quick startup time" - Just measure total time
• "Standard profiling" - Startuptime log + basic analysis
• "Deep analysis" - Full profiling + agent analysis + recommendations

3. Run Startup Profiling

Execute neovim with profiling:

Create startup log

nvim --startuptime /tmp/nvim-startup-$(date +%s).log --headless -c 'qa!'

Store log path for analysis

Use Bash tool to run command.

4. Analyze Startup Log

Read the startup log and analyze:

Quick Analysis:

• Total startup time (last line)

• Compare against targets:

• Excellent: < 30ms

• Good: 30-50ms

• Acceptable: 50-100ms

• Needs work: > 100ms

Standard Analysis:

• Total time

• Top 5 slowest items

• Plugins loading at startup

• Heavy configuration functions

Deep Analysis:

• Complete breakdown by phase

• All items > 5ms

• Plugin load reasons

• Suggested optimizations

Use Read tool to parse log file.

5. Run Lazy.nvim Profile (if available)

Check if lazy.nvim is installed:

nvim --headless -c "lua if pcall(require, 'lazy') then print('LAZY_AVAILABLE') end" -c 'qa!' 2>&1

If available, suggest running :Lazy profile interactively or use agent for analysis.

6. Delegate to Performance Analyzer Agent

For deep analysis, use Task tool:

Use performance-analyzer agent to:

• Analyze startup log in detail
• Profile lazy.nvim if available
• Identify optimization opportunities
• Generate specific recommendations

Agent has access to:

• Read (for config files)

• Bash (for nvim profiling commands)

• Write (for generating reports)

7. Identify Bottlenecks

Common bottlenecks to check:

Heavy init.lua: Look for slow sourcing of init.lua (> 5ms)

Too many startup plugins: Count plugins loading at startup vs lazy-loaded

Slow plugin configs: Identify setup() functions taking > 5ms

Treesitter compilation: Check if parsers are compiling at startup

LSP initialization: Check if LSP servers loading immediately

Use Grep and Read to check config files for these patterns.

8. Generate Recommendations

Based on findings, provide specific fixes:

For slow plugins:

-- Current (loads at startup) return { "nvim-telescope/telescope.nvim", }

-- Recommended (lazy-load) return { "nvim-telescope/telescope.nvim", cmd = "Telescope", keys = { { "<leader>ff", "<cmd>Telescope find_files<cr>" }, }, }

For heavy configs:

-- Current (heavy setup at startup) return { "plugin/name", config = function() -- Complex setup code end, }

-- Recommended (defer loading) return { "plugin/name", event = "VeryLazy", config = function() -- Same setup, but deferred end, }

For missing priority:

-- Current return { "folke/tokyonight.nvim", config = function() vim.cmd("colorscheme tokyonight") end, }

-- Recommended return { "folke/tokyonight.nvim", priority = 1000, -- Load first! config = function() vim.cmd("colorscheme tokyonight") end, }

9. Present Results

Show results in clear format:

Performance Analysis Results

Startup Time: 45.2ms (Good ✓)

Performance Breakdown

• Initialization: 3.2ms (7%)
• Plugin loading: 18.5ms (41%)
• Configuration: 15.3ms (34%)
• UI render: 8.2ms (18%)

Slow Items (> 5ms)

1. telescope.nvim - 12.3ms (loading at startup)
2. nvim-treesitter - 8.9ms (expected, syntax highlighting)
3. lualine.nvim - 5.1ms (acceptable, UI component)

Optimization Opportunities

High Priority:

1. Lazy-load Telescope (saves ~12ms)

   • Add cmd and keys triggers
   • Location: lua/plugins/telescope.lua

2. Defer todo-comments (saves ~3ms)

   • Add event = "VeryLazy"
   • Location: lua/plugins/todo-comments.lua

Medium Priority: 3. Optimize LSP loading (saves ~2ms)

• Load by filetype instead of startup
• Location: lua/plugins/lsp.lua

Estimated Improvement

Applying all recommendations: 45ms → 28ms (38% faster)

Would you like me to apply these optimizations?

10. Offer Optimizations

If issues found, ask:

How would you like to proceed?

• Apply all optimizations automatically
• Show me the changes first (recommended)
• I'll do it manually
• Generate optimization script

If user wants changes:

• Show exact file modifications

• Use Edit tool to apply

• Verify syntax is correct

• Recommend re-testing

11. Generate Report (Optional)

If --detailed flag or user requests, create markdown report:

Write detailed report

Use Write tool to create /tmp/neovim-performance-report-<timestamp>.md

Report includes:

• Full startup log analysis

• All items with timings

• Plugin-by-plugin breakdown

• Optimization recommendations

• Before/after comparison

• Links to relevant documentation

12. Suggest Re-Test

After optimizations:

To verify improvements, run: nvim --startuptime startup-after.log --headless -c 'qa!'

Or re-run: /analyze-performance

Advanced Analysis

Memory Profiling

If requested, check memory usage:

nvim --headless -c "lua print('Memory:', collectgarbage('count'), 'KB')" -c 'qa!'

Plugin-Specific Profiling

For specific slow plugin, suggest:

:Lazy profile " Interactive UI

Continuous Monitoring

Suggest creating startup benchmark script:

#!/bin/bash

benchmark-startup.sh

for i in {1..10}; do nvim --startuptime /tmp/startup-$i.log --headless -c 'qa!' tail -1 /tmp/startup-$i.log | awk '{print $1}' done | awk '{sum+=$1; count++} END {print "Average:", sum/count "ms"}'

Tips

• Load lazy-nvim-optimization skill for deep profiling knowledge

• Reference neovim-best-practices for optimization patterns

• Be specific about locations and line numbers

• Show before/after comparisons

• Test recommendations before suggesting

Settings

Check .claude/neovim-advisor.local.md for:

neovim_path: ~/.config/nvim performance_target: 40 # Target startup time in ms

Example Usage

User: /analyze-performance

→ Run profiling → Analyze results → Show recommendations → Offer to optimize

User: /analyze-performance --detailed

→ Deep analysis → Generate full report → Specific recommendations

Important

• Always create temporary files in /tmp/

• Clean up profiling logs after analysis

• Never modify config without permission

• Verify nvim commands work before running

• Handle errors gracefully (nvim not found, etc.)

Provide actionable, specific performance optimization guidance to help users achieve fast startup times.