Ways for functional ui testing and speed testing of an website

I'm trying to compare two architectures to see which one is faster and beter. The first one in an Angular front-end calling an .Net Core API + CosmosDB with DocumentDB api and the second one is an .NET MVC + SQL website. Both website's have the exact same features, design and functionality.

Now I am struggling to get a good set of tests to compare this two. And also I can't seem to find good software or ways to use for my test.

What I actually want is for example to automatically open browser go to URL do some stuf en stop timing. And this for let say 100 times.

I tryed to use Seleno and Selenium without Seleno, but too old and not working any more.

Please help me out. What can I do?