I have slow downloads too (with google DNS), but I would think this wouldn't impact it much. It's not like it's performing a DNS lookup for each chunk, right?
Well no, the issue is that the ps4 is constraining the tcp receive window (which is how much data is in flight at once), so if your ISP DNS gives you a CDN node that's 200ms away but google's DNS gives you a CDN node that's 10ms away, you get receive_window bytes every 10ms instead of every 200ms.
There's a similar thing happening (different DNS giving vastly different experience) with Netflix as well: Netflix has local nodes _inside_ many ISP's networks, close to ISP subscribers. If you use your ISP's DNS (and if they're doing their job properly), they'll send you to one of the local nodes and it'll take much less time to buffer, your stream will start faster, you'll drop less etc. Whereas if you use Google's DNS, they don't (necessarily) know the inner workings of your ISP so they send you to a generic Netflix CDN node that's near-ish but still probably 10-100x "farther" as the photon flies.
If you want to have a mix of DNS settings per domain name, you can set up a dnsmasq inside your network and configure it to recurse to google's DNS normally but recurse to your ISP's DNS for just netflix.com, nflxvideo.com etc. see for instance [0] for one way to set that up. they have it running on a dd-wrt router but I have it running just on some rando linux machine somewhere in the house and configure my DHCP to tell everything to use that machine's IP as the primary DNS.
Hmmm, does that actually improve speeds for Netflix, or was that somebody just doing it because they thought it would?
It's been a while since I've looked into it, but I thought that Netflix's devices peer with the provider's routers and intercept traffic through that way, so the DNS server shouldn't matter (because they would share the same IPs as the publicly accessible CDN load balancers).
I thought most CDNs worked that way now - using DNS never really worked well.
Anecdata: Office 365 will put you on an APAC CDN instead of an AU CDN if you use Google Public DNS from Australia, but not so if you use local ISP DNS (like, say, Telstra's).
