I have read this guide: Link and have found this article to be quite interesting. My question is if I configure my router to block internet ads using this guide, how will this slow down my router? The way I understand it is when I visit a website, that website will have to check the site against a "blacklist" that is in the router, will this have a significant impact on a site's loading speed?
Practically, no. All it would do would be to redirect any requests to these sites to a local domain serving a trivially small file. While there will be some (negligible) additional load to the router, this should be inconsequential, and no different from running an ad blocking proxy or some flavour of adblock.