Hardware, OS, and multiplexing guidelines for on-premises performance testing robots, including CPU and RAM ratios by workload type and Virtual Machine baseline recommendations.

These are the recommended system requirements and configuration guidelines for running performance testing robots in an on-premises environment. These recommendations are based on UiPath internal benchmarks and field investigations.

Performance testing robots rely on multiplexing, meaning multiple Virtual Users (VUs) can be executed in parallel on the same machine.

The number of VUs a single robot executes simultaneously is called multiplexing factor (for example, 10 VUs in parallel equals to multiplexing factor 10). The multiplexing factor is different per automation type.

Effective multiplexing depends on:

API Automations do not require a browser, but the above OS requirement still applies.

These baseline ratios apply most directly to Web workloads. API workloads often achieve higher VU density per core/GB due to lower rendering overhead. Workloads should be validated via dry run and full execution before finalizing sizing.

Capacity Planner runs a short series of progressive load probes against your actual hardware and extrapolates a virtual-user recommendation. The ratios above serve as a planning baseline before your first dry run, and Capacity Planner can then validate and refine that estimate for your specific environment.

Capacity Planner calculates the recommendation via least-squares regression across probe results, then discounts it by a factor of 0.85 on the CPU slope to build in headroom. Guardrails cap the recommendation at CPU ≤ 96% and RAM ≤ 90%, with additional hard caps by application type.