Safari does not play well with ipv6. Slow, Sluggish...

(besides switching browsers) Is there are way to fix the issues with Safari 10.1.10 and ipv6?

With ipv6 turned on Safari is sluggish an skips, jumps and makes using it intolerable. Turn off ipv6 and it's much better but many new sites don't function properly without ipv6 (menus won't work, backgrounds are wonky and such).

I am stuck at 10.6.8 because of proprietary hardware / software that I use and I can't believe that they stopped at a point where Safari is broken for normal use.

So, is there any known fix for Safari or a way to go backward to one that works or should I just give up and switch to Chrome?