Site speed is an important element of SEO as it’s a contributing factor in the overall user experience matrix - as such it relates directly to both Google’s Core Web Vitals update which looks at key elements of speed including page load time & shift & the Page Experience update which looks at how users are able to interact with a page - essentially their overall experience.
Measuring site speed is an important part of any SEO audit & there’s a range of tools that we can use for this ranging from Google’s own PageSpeed tool, through to Lighthouse, through to external tools such as GT Metrix which allow for a waterfall analysis - essentially identifying areas & elements which are causing a hold up within the load time & identifying how we can improve these. Using these tools together to produce an overall speed report is a great way to help improve the performance of the website & identify the quick wins first to balance impact vs resource/cost.