> For the complete documentation index, see [llms.txt](https://docs.does.qa/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.does.qa/configuration/max-concurrency.md).

# Max Concurrency

Max Concurrency controls how many test cases run at the same time. Higher concurrency usually means faster overall runs. Lower concurrency can help when your application or a third-party service struggles under load.

You set this in **Settings → Runners**, under **Concurrency Limits**.

## Choose how fast to run

For each concurrency setting you can choose:

| Option                | What it does                                                        |
| --------------------- | ------------------------------------------------------------------- |
| **Fastest Runs**      | Run as many test cases in parallel as your account's runners allow. |
| **Limit Concurrency** | Cap how many test cases run at once, using the slider that appears. |

## Two related settings

| Setting             | What it controls                                      |
| ------------------- | ----------------------------------------------------- |
| **Max Concurrency** | The overall cap across all runs that are in progress. |
| **Run Concurrency** | The cap for a single run.                             |

If only one test case seems to be running at a time, check these settings first. Also check how many [test runners](/getting-started/terminology.md) your account has: each runner can run one test case at a time.

{% hint style="info" %}
**Pro tip:** Lower concurrency temporarily when testing against a shared staging environment, rate-limited APIs, or login flows that reject too many sessions at once.
{% endhint %}