Why Removing Unused MCP Servers Speeds Up Claude Code More Than Removing Skills
Why Removing Unused MCP Servers Speeds Up Claude Code
If Claude Code feels slow to start up or sluggish during sessions, the first thing to check is how many MCP servers you have configured. Trimming unused ones made way more of a difference for us than removing skills.
The reason is simple: MCP servers are actual processes and they all have to handshake on startup.
Skills vs MCP Servers
Skills are essentially prompt templates with some metadata. Loading a skill means reading a markdown file and adding it to the context. This is fast - a few milliseconds per skill, and they only consume tokens in the context window.
MCP servers are different. Each one is a separate process that Claude Code spawns and maintains:
- Process startup. Each MCP server launches as its own process (Node.js, Python, or whatever runtime it uses).
- Handshake. Claude Code sends an initialize request and waits for the server to respond with its capabilities.
- Tool registration. The server reports all its available tools, which get added to Claude's context.
- Keepalive. The process stays running for the duration of the session, consuming memory.
With 15 MCP servers configured, startup involves spawning 15 processes and completing 15 handshakes. If any server is slow to initialize (common with servers that need to authenticate with external services), it blocks the entire startup sequence.
The Practical Impact
We went from 12 configured MCP servers down to 4 that we actually use regularly. The result:
- Startup time dropped from 8-12 seconds to 2-3 seconds.
- Context window usage decreased because fewer tool definitions were being injected.
- Session stability improved because fewer background processes meant fewer random crashes.
What to Keep
Keep the MCP servers you use daily. For everything else, remove them from your configuration and add them back when you need them. The 30 seconds it takes to re-add a server config is less than the cumulative startup delay of keeping it loaded for every session.
The same principle applies to Fazm - we keep the MCP server count minimal and focused on the tools the agent actually needs for the current task.
- MCP Server Debugging - Initialize Handshake
- MCP Server Management - Fewer Is Better
- Skills vs MCP vs Plugins Explained
Fazm is an open source macOS AI agent. Open source on GitHub.