> 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

Control how many test cases run in parallel.

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 %}