From my side plusnet dns is ok atm and has been now for about a week, but i mostly use opendns, i'll post those for you below with figures of how other dns servers are performing for me as well.
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Nameserver Response Time (ms)
min/avg/max/stdev/retries
212.159.6.9 18.41/19.16/19.79/0.46/0 plusnet
212.159.6.10 18.65/20.50/23.16/2.01/0 plusnet
208.67.222.222 18.21/18.29/18.44/0.09/0 opendns
208.67.222.220 17.95/18.13/18.39/0.16/0 opendns
208.67.222.123 17.91/18.31/18.57/0.22/0 opendns-family-safe
208.67.220.123 17.75/18.30/18.56/0.30/0 opendns-family-safe
8.8.8.8 23.66/24.14/24.77/0.44/0 google
8.8.4.4 17.98/18.14/18.54/0.21/0 google
4.2.2.1 17.86/36.94/111.35/37.21/0 level3
4.2.2.6 17.90/18.05/18.34/0.15/0 level3
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So from the top, plusnet dns is ok ish as expected because they dont have a MASSIVE server farm to rely on. Next is opendns and opendns family-safe those almost always give me great service unless the routing changes, which happens here and there, but these guys do have MASSIVE server farms so are mostly reliable and fast. Next is google, same thing as opendns really but not a personal choice for me.
And last is level3, again massive resource but i've found for me at the moment as you may see that the figures are slightly elevated and have a spike thing going with lots of failed requests, so they would not be beneficial for me to use.
Some people use this little program as well to find servers, as well as test your own if you have them.
https://www.grc.com/dns/benchmark.htm however i do find it very harsh on my router which tends to flood the router for some reason, and in doing so gives me false information.
So i prefer to use ns_bench which is a none gui program which gives you the raw figures you see above. Or for quick tests i would use another program called Dig.
Hope this helps you choose some dns-servers if you feel you should need to, but i suspect plusnet-dns is not your problem for slow loading pages at this moment in time.
