Most people won't notice a speed increase. But it will help if your ISP's DNS servers are slow or broken, or if you tend to visit sites that aren't popular among your ISP's other customers.

Caching DNS records for a long time locally can have adverse effects. Large sites with multiple webservers like Google use very short DNS TTL times (Google uses 5 minutes) for load balancing and redirecting traffic during disasters and maintenance.

So if you don't need it, don't use it. Most of the time the forwarding DNS server of your local ISP is close enough that you won't see any speed increase at all.

You're right, lammert, nobody should "cache DNS records". You should query a DNS server every time. I thought the article was instructing on how to run a real DNS server locally, which is easy to do.