Cursor "Context Length Exceeded" and Slow Requests: Keep the AI Fast and Accurate

Cursor shows context length exceeded, requests crawl, or the model forgets earlier decisions in a long chat. Context management is the main friction point in AI coding tools — not a broken install. Keep each thread focused and only pull the files you need.

Why Cursor slows down or hits context limits

One giant chat that accumulates every file, diff, and reply
@-mentioning whole folders or the entire codebase when a few files would do
Huge pasted logs or generated files in the prompt
Asking for a multi-module refactor in a single message

Fix 1: Fresh chat per task

Start a new chat when you switch features or bugs. Long threads burn context on old decisions and make later answers slower and less accurate. Carry forward only a short summary of what still matters.

Fix 2: @-mention only what you need

Prefer specific files over broad folders:

Good: @src/lib/content/posts.ts and the one component you are editing
Costly: @src or the whole repo on every turn

Add folders only when the task truly spans many files.

Fix 3: Add a .cursorrules (or project rules) file

Put durable project constraints in rules so you do not re-paste them every chat. Example starter:

# Project rules
- Prefer editing existing patterns over new abstractions
- Do not add dependencies unless asked
- Match existing file structure and naming
- Keep diffs small and task-scoped

Adjust to your stack. Rules shrink how much you must restate and keep answers on-rails.

Fix 4: Split large work; pick the right model

Break “refactor the whole auth system” into smaller prompts (types → API → UI).
For big refactors that need many files, use a model with a larger context window when available.
Paste the exact error back into a short new chat instead of scrolling an old thread.

Quick checklist

New chat per distinct task
@-mention specific files, not the whole tree
Project rules / .cursorrules for standing constraints
Smaller prompts; larger-context model for wide refactors