All good stuff there jimp.. And I agree with you for a specific record. Yes it might be faster to forward to somewhere that has it cached.
But what is the round trip time of that query, even if cached to that NS your forwarding too.
What is the TTL of the specific record? What is the TTL of the NSers down the tree.. So lets say I am looking up www.domainX.tld, once the resolver caches the NS for domainX.tld.. As long as that TTL is valid it does not have to go ask anything up the tree. He has cached the NS for domainX.tld cached. So if looking for record www, he just has to go direct to the NS for domainX.tled.
Which you never know might actually be quicker to respond than who your forwarding too ;) Even if that forwarder has it cached, if he doesn't then he has to either forward it or resolve it.. Which for sure could be slower than you just directly asking the NS for domainx.tld for www
So lets say the ttl on www is 5 minutes. So when your resolver looks it up again the ttl is always going to be 5 minutes.. But depending on exactly when your client asks for it and what the forwarder ttl time is.. And then when your client(s) ask for it again. You could actually cause 2 wan queries for it when you would of only needed 1 if you would of just resolved it.
If you get back a expiring ttl of 1 min, you can only cache it for 1 minute.. So if you have another client on your network ask for say at 2 min now you have to go ask the forwarder again. But if you would of resolved it you would of had full 5 min ttl. So your client that asked for it at the 2 min mark would of just gotten a cached value and a 3 min ttl for his cache.
Yes your dnssec is going to add some time to your overall speed, etc.. But to be honest in the big picture you really should just run a resolver, unless you have some specific issue why you can not, like your isp intercepts dns, etc. Or you have just really bad latency and don't want the added over head of walking down the tree from roots and extra overhead of dnssec.
But once you get your cache going and depending on the actual use of your clients.. The difference that you might have now and then from having to resolve vs forward, with the added benefit dnssec, I don't see how couple ms here or there make a difference.
To be honest if the user is looking speed up their internet because they think the resolver is slowing them down - then they prob have more issues than a couple extra ms to lookup something.