I came across this SC performance and tweaking guide by YouTuber 'BoredGamer' and the results are astounding.
Guide No.1: https://www.youtube.com/watch?v=U8K9Xfn6YlQ
Guide no 2: https://www.redacted.tv/how-to-set-up-star-citizen-performance-guide/
Previously, my son could only run SC in 1080p at the lowest graphic setting, now he's running it at 1080p with the highest graphic settings and its smoother than before.
It took about 40 minutes to complete the process, but the results are clearly worth the effort. If this has been posted before then apologies in advance.