Champion select bug

Whenever I load into champion select i start to lag a lot. When I click accept to accept a ranked game it only shows some people not all of them. I load in to champ select and we are already on our second pick. This happens about 25 percent of the time I try to play. I am playing on a mac is that helps and I don't know how to fix it. Riot or someone that has had this issue please help me.