What should a person do if he finds himself in a prayer quorum (minyan) in which the prayer leader (chazan) prays too quickly: Find another minyan, demand that the pace be slowed or the chazan replaced?

If you are the only one dissatisfied with the pace of the davening, then the best solution is to find another minyan. It is important to make every effort to avoid a machloket [=quarrel], since creating an unnecessary machloket is a serious offence.