Oh yeah! I found useful information in this WordPress Optimization Bible by Vladdimir Prelovac. A few minutes tweaking the MySQL database for Island in the Net and my website had a very improved Google PageSpeed Insights.
query_cache_limit = 2M
query_cache_size = 256M
query_cache_type = 1
It is noticeable... but, tbh, this site has always been a bit slow. It could be faster me thinks...
I've moved to a new VPS but may need to upgrade memory and CPU.