// 22 tips in Performance
Getting faster responses and better results.
When Claude starts referencing files you've since deleted, remembering old code you've already changed, or getting confused by contradictory instructions from a long session — type /clear to wipe the slate clean. Unlike /compact which preserves context, /clear gives you a true fresh start without restarting the CLI.
Not every task needs deep reasoning. Type /fast to switch Claude Code into fast mode — same model, faster output — for quick edits, simple questions, and routine changes. Toggle it off when you need Claude to think harder on complex problems.
Long sessions eat through your context window as conversation history piles up. Type /compact to summarize the conversation so far and reclaim space — keeping Claude's understanding of what you're working on while freeing up room for more work.
Type /cost at any point to see how many tokens you've used in the current session, how much it's costing, and which operations are consuming the most context — so you can make informed decisions about when to /compact, /clear, or switch models.
Pass --model when starting Claude Code to choose exactly which model you want — opus for complex architecture work, sonnet for everyday coding, haiku for quick lookups — without changing your default settings or switching after the session starts.
Type /fast to switch Claude Code into faster output mode — same model, faster generation. Perfect for quick lookups, simple edits, and rapid-fire questions where you don't need Claude to think as deeply before responding.
When you've finished one task and want to start a completely different one, run /clear to reset the conversation — Claude forgets the previous context so stale decisions, old file reads, and irrelevant discussion don't pollute your next task.
Open multiple terminal tabs and run separate Claude Code sessions simultaneously — one fixing tests, another writing docs, another refactoring a module — each working independently so you get three tasks done in the time of one.
When your Claude Code session gets long and responses slow down, run /compact to summarize the conversation history and free up context window space — keeping your session alive without losing important context.
Use Esc+Esc and choose "Summarize from here" to compress only the noisy middle of a session while keeping your original context and instructions intact.
Fast mode makes Opus 4.6 respond 2.5x faster at a higher cost per token. Toggle it with /fast for live debugging and rapid iteration.
Claude Code runs on 5-hour rolling windows that start from your first message — send a lightweight wakeup message at 6am to unlock three windows per day instead of two.