By supporting the Web Driver Sampler plugin for Apache JMeter, Azure Load Testing lets you collect and analyze the performance metrics as experienced by the end user.
You can measure the browser response time that includes the time taken for JavaScript execution, CSS transforms, etc. You can use the Web Driver Sampler with a minimal load along with the other samplers in your test script to gauge the end user performance metrics while the backend is under load.
Learn more about the supported Apache JMeter features in Azure Load Testing.