I can help. I am an expert in this specific field of speed optimization and own a company from Romania doing exclusively ADVANCED speed optimization. ([login to view URL])
I only deliver ADVANCED optimizations, not medium ones. The market price for ADVANCED optimization is 500-1000$. I can do it for 275$. I guarantee that this will be an ADVANCED optimization (render blocking removed, plug-in prioritization, all specific problems solved, etc.), not a medium one. Unlike a medium optimization that can be done in a couple of hours, an ADVANCED one will take at least 2 - 3 days of non-stop hard work.
An advanced optimization will pay itself back fast due to these statistics: [login to view URL]
Also, note that GTMetrix, Pingdom and Google PageSpeed Insights are just "best practices" tools. They do not measure real speed for real users, they are "synthetic tools". The only test that measures real speed for real users is [login to view URL] - tool for professionals developed by Google. That is the tool by which you should judge the effect of a speed optimization. Those selling you grades on the other 3 testing tools are either scammers either most probably don't know what they are doing. Most are web designers also bidding on such projects, they're not real speed optimizers. For more about how to properly measure speed, check my Medium article: [login to view URL]@turbowebro/is-google-page-speed-insights-an-accurate-tool-for-testing-your-website-speed-10d82e00d58c