It could be that your ISP or the peering network carriers have configured suboptimal routing for the OpenDNS anycast addresses, or that your IP address is deemed to be at the wrong location. There's no easy way to resolve this.
If you want me to analyze this further, you would have to tell me your location and to post the complete plain text output of the following diagnostic commands here:
nslookup -type=txt debug.opendns.com.
tracert 208.67.222.222
nslookup facetime.com.
