Mac Safari running slow / slow to start loading page?

My Mac Safari has been running slowly for a bit - it seems to take ages to start loading the page.

Firefox has no such problem - so I'm pretty sure my ISP is OK (I have fibre at approx 40Megs)

So, with thanks to http://www.webnots.com/fix-safari-slow-loading-pages-mac-os-x/ I found the following seems to have fixed my problem.

Disable the DNS Prefetching in Safari:

1	defaults write com.apple.safari WebKitDNSPrefetchingEnabled -boolean false (You can re-enable it by doing: 1 defaults delete com.apple.safari WebKitDNSPrefetchingEnabled) Simple as that - don't even need sudo! Just restart Safari and off you go. (For info, MacBook Pro 15" running Sierra)