# On-premises robot system requirements

> Observe 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.

Observe 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.

## Multiplexing

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 (e.g., 10 VUs in parallel equals to multiplexing factor 10). The multiplexing factor is different per automation type.

* API automations support the highest multiplexing factor due to being CPU/lightweight and I/O-bound. Typical ranges are 20–100+ VUs per CPU core, depending on API payload size.
* Web automations support multiplexing.
* Desktop automations are restricted to 1 VU per machine because of Windows session constraints.

Effective multiplexing depends on:

* CPU architecture/performance and available RAM
* Workload type and complexity (API > Web >> Desktop for multiplexing potential)
* System overhead and background services
  :::tip
  Use separate robot pools for API vs. Web workloads to tune multiplexing independently and avoid resource contention.
  :::

## Virtual machines

* Use compute-optimized VMs with strong CPUs and SSD storage.
* Recommended baseline: 16 physical CPU cores, 32 GB RAM, SSD.
* Alternative (lower-efficiency) setups: 4 cores / 8 GB RAM or 8 cores / 16 GB RAM.
* Keep virtual machines clean of unnecessary background services.

## Software and operating systems

* Windows Server 2022 or newer
* Google Chrome installed (latest stable) for Web Automations
  :::note
  Trouble: When running Web Automation on premises (using local machines), make sure you set up group policy correctly. Go to Studio Desktop, navigate to **UiPath Extensions** > **Chrome**. If the **Group Policy Online** value is not set, uninstall the plugin, and select **Group Policy Online** during installation. For more information on policies, refer to [Studio - Group Policies](https://docs.uipath.com/studio/standalone/latest/user-guide/chrome-group-policies).
  :::

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

## Resource ratios

* CPU: 0.5–1.8 VUs per physical core (measured on 16 physical cores)
* RAM: 0.5–2 VUs per GB RAM (measured on 32 GB)
* Count physical cores only; hyper-threading provides little benefit under sustained load

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