There's a test at http://test-ipv6.com http://test-ipv6.com that will give you a aggregated (or detailed if you wish) report of influence of IPv6 upon both IPv4

There's a test at http://test-ipv6.com http://test-ipv6.com that will give you a aggregated (or detailed if you wish) report of influence of IPv6 upon both IPv4 and IPv6 in your configuration. Its goal is to help you troubleshoot some problems even if you have only IPv4.