I'm using IPv6 through a SixXS tunnel and apart from two sites it works well. The two problem sites are as mentioned above, Facebook is just insanely slow for the first connection and I'm not sure why, health.govt.nz is completely unreachable for me because they filter icmpv6. I've discussed this with various people and I'm fairly confident that the problem is not at my end.

So, any thoughts on how I might configure my system (debian 6) to prefer IPV4 for just those two sites but use ipv6 for everything else?