How do you monitor the impact of website performance on conversion rate?

There are tons of white papers out there, companies who say that their clients converted better thanks to better load times, and of course sell tools to monitor web performance. But the workflow is too tedious for me. I have to look at tons of dashboards on different metrics and segments, to at best "imagine" what I could optimize. So, do you know of any good tool for this problem? A tool that would identify any performance problem impacting our user's retention/conversion?