Just to clarify a few things:

Do you know what a DNS server is and what it does? 

"An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. For example, the domain name www.example.com translates to the addresses 192.0.32.10 (IPv4) and 2620:0:2d0:200::10 (IPv6)."

You won't NEED to change DNS servers unless you're moving. Upgrading speeds won't change that, but the ISP's DNS servers aren't always the fastest. Like I mentioned in the other post there are free public DNS servers anyone can use like Google, FreeDNS, OpenDNS and so on.

I've been using 4.2.2.3 (Primary) 4.2.2.5 (Secondary).

Here's a short list:

Google DNS:

8.8.8.8

8.8.4.4

DNS Advantage:

156.154.70.1

156.154.71.1

OpenDNS:

208.67.222.222

208.67.220.220

VNSC-pri.sys.gtei.net:

4.2.2.1

4.2.2.2

4.2.2.3

4.2.2.4

4.2.2.5

4.2.2.6