I have colleague that is on this whole kick of disabling IPv6 while leaving IPv4 on each new machine that comes in before deploying in our environment. He takes his personal anecdotal evidence and claims that disabling IPv6 helps with network perfomance because there's less "advertising/request" packets the backbone and the nodes have to process. He then quickly adds that it also creates less of a surface area in which attackers could potentially try to attack.
While these arguments sound good on paper, I question the anecdotal evidence provided and the security "precaution" that disabling IPv6 may provide. Heck, I even found this post where one of the posters mentions the IPv6 could even provide a marginal improvement. Differences in networks aside, do these claims hold water?