Game freezes after loading - can't pick from first carousel

After loading, my game freezes for about 10 to 15 seconds, which means I can barely pick one of the champions directly in front of me from the carousel or sometimes nothing at all. I already set all graphics settings to the lowest possible value and run the game in windowed mode. My PC is a few years old already, but this doesn't happen for me on Summoner's Rift / in other game modes even on high graphic settings. Some other people in my TFT games reported the same issue.

Having a few extra seconds at the start of the game before being able to pick from the first carousel would be great - I basically won't be able to play ranked TFT if this persists. To balance this out, the preparation for the first minion round could be half as long or something - there's nothing to do anyways, especially because one's champion gets placed on the board automatically. (This would also make being AFK / tabbed out for the first few seconds of the game less punishing; I usually see at least one other guy that isn't fast enough to pick from the first carousel.)