This is a change to the LeadApe set on Infernape's analysis.
http://www.smogon.com/dp/pokemon/infernape
The set recommends running no more speed than needed to outrun positive natured base 100s because
"Due to the defense drops from Close Combat, any encounter with a fellow Infernape will almost always result in the slower ape winning, so in general, it is a poor choice to increase Infernape's Speed any further." (quote)
I believe that this is poor advice because if a player is aware of this fact they will use Fire Blast rather than Close Combat. The slower Infernape will then be in KO range and can be defeated, assuming the same set is used on both Pokemon. You will always win unless you miss repeatedly, and your Fake Out blocks theirs and saves your Focus Sash.
So, the opposite is true. The
faster Infernape will usually win, not the slower one, and advising against it for no other specific reason is not good. If there is something I'm missing here, the sentence should be clarified, or if not, changed.