[CLIENT] Incredibly slow loading after champion select (pre-game)

After champion select, the client closes, and the game loads. The screen stays black for 20 seconds before the champion outlines appear. Things like champion pictures, summoner icons, and names etc. each come every 10 seconds, one at a time. And then, every 10 seconds, the percentage increases by 1 for each summoner, one at a time. The image provided shows what I see when I'm at 95% on another summoners screen. I've never sat at the screen long enough too see if I ever load into the game. I've only tried this in custom games, but for the 5 custom games I've made, this has happened. I've repaired my installation, and completely reinstalled League of Legends. The issue persists. Steps to reproduce: 1.Create a custom game. 2.Select any champion.

This happens, regardless of whether I'm playing by myself or with others. I haven't tried this in a draft pick as I fear I would get a ban.