Improvement in Core Web Vitals - Speed and Performance

I am looking for a company that is well versed in website performance. My websites have taken a significant drop since Google’s last algorithm change in November. NitroPack plugin has been on both sites now for at least eight months, and it helped then, but it doesn’t seem to be enough now. I am looking for a company with competence in website performance and speed to get my websites (2) to where they should be.