BrowserStack provisions and scales the load generators for you. A slowdown usually points to your application or its infrastructure. Use these signals in your test report to identify the cause:
Signs your application is the bottleneck:
* Response times rise while throughput flattens or drops as virtual users (VUs) increase.
* 5xx errors, timeouts, or connection resets increase with load.
Signs of a network or traffic control issue:
* Errors appear from only one load zone.
* 429 errors or blocked requests indicate a rate limiter, WAF, or CDN is throttling test traffic.
To confirm the bottleneck:
* Run a baseline test with a few VUs and compare it with your full-load run.
* Correlate the test window with your server-side monitoring (CPU, memory, database connections).
If you're still unable to identify the bottleneck, contact BrowserStack Support for assistance.
