Chris

No, it can't. All a DNS service does is convert the web address you use (e.g. bbc.co.uk) into the numerical address the internet uses (e.g. 212.58.224.138). Your ISP provides one, that is used by default unless you change your internet connection settings. If you alter your settings to allow you to use OpenDNS's service instead, every time you request a web page the OpenDNS service will first check to see what (if any) blocklists that webpage might be on. If it's not on any blocklists you have specified should apply to your network, it will return the numerical address for the page you require and your browser can then load it. If it named on any lists you have chosen to apply to your network, then it will instead serve you a page explaining that it is blocked and why it is blocked. Either way, the process takes only milliseconds and is frequently faster than the DNS service provided by your own ISP.

OpenDNS's involvement ends with the provision of the numerical address of the page you want to load. After that, the throughput you get while load ing that page is nothing to do with OpenDNS