Use Visual Studio Performance Profiler for OpenSilver projects.

.NET profiling tools can be used to analyze OpenSilver application performance including CPU usage, Memory Usage and other available analysis Visual Studio provides.

1. Install profiling tools

By default profiling tools are installed with Visual Studio. If that's not the case then it can be installed using Visual Studio Installer.

Install NET profiling tools

2. Use latest Simulator project

.Simulator project needs to be set as Startup Project in order to be able to use profiler. As an addition simulator project needs to be updated to the latest version which means it needs to run as a standalone executable Windows Application.

Here are full instructions.

3. Run profiler

If the above mentioned points are satisfied then to run profiler go to Debug -> Performance Profiler...

Performance Profiler Menu

Profiler tools

Select profiling tool and click Start. Diagnostics information will be generated after closing the simulator.

Here are some examples of CPU Usage diagnostics.

Profiling result

CPU usage

4. Specify .pdb files location

If the result doesn't show OpenSilver external calls then most probably profiler couldn't find .pdb files for OpenSilver.

Follow the instructions to specify .pdb files location in Visual Studio. One other option would be to copy OpenSilver.pdb in Simulator Debug folder.

This document describes all profiling tools in depth.
Measure app performance in Visual Studio