The average load time for a website is 2.5 seconds. The added load time from running your own recursive resolver, which is only added the first time the site is loaded, would be around 50ms, or 2% increase load time.
DNS resolving is not a major aspect of a typical websites load time. If you want to speed things up, run a local proxy which local cached version of all popular web frameworks and fonts, and have it be be constantly populated by a script running in the background. That will save you much more than 2% on first load.