Parallel Claude Instances

The biggest productivity multiplier in Claude Code is not a better prompt or a smarter model. It is running multiple instances simultaneously. While Instance A processes a complex refactor, you are building context in Instance B for the next task. While Instance B plans an approach, Instance A finishes and presents its results. You are always working, always reviewing, always moving forward. The bottleneck shifts from "waiting for Claude" to "triaging which result to review next." That is a fundamentally better problem to have.

The key to parallel instances is task independence. Each instance should be working on a task that does not depend on the output of another instance. Feature A and Feature B on separate branches — perfect. Frontend changes and backend API simultaneously — perfect. The auth refactor in one instance and the tests for the auth refactor in another — problematic, because the tests depend on the refactor being done. Think of each instance as an independent contractor. They can work in the same building, but they should not be waiting on each other's deliverables.

In practice, most developers can productively manage two to four parallel instances. Beyond four, the context-switching cost of reviewing and directing that many streams exceeds the throughput benefit. Start with two — your "primary" task and a "background" task. The primary gets your active attention. The background gets a long-running instruction ("refactor all the test files to use the new pattern") that does not need moment-to-moment guidance. As you get comfortable, add a third for ad-hoc quick tasks.