MCP server slowness comes from two places: cold-start time and per-call latency. Cold-start (5-10 seconds before tools appear) almost always means npx is downloading the package on every restart — fix it by installing globally with npm install -g or locally with npm install --save-dev and calling the binary directly. Per-call latency usually means the tool is making a network request or slow query — add caching or prefetch data on startup.
MCP servers should connect in under a second and respond in under two. When they do not, the cause is almost always one of four things — here is how to find it and fix it.