Sometimes My Game Doesn't Load In at All

[CRASH, CLIENT] My Game Say It Loads in and Keeps me on the Loading Screen Even Though I'm at 100%

I've experienced this a lot in the past 3 months and didn't really think too much of it. I would get into a game and when in the loading screen my game would take a significantly long time to load in, sometimes taking up to 3-4 minutes. However, about two months ago my game would finally load in and say I was at 100% and then not get into game. This would result in me waiting at 100% for about a minute before quitting out of league to reopen the game, and because of the long loading time, I wouldn't get into game until around 5 minutes. I didn't report it earlier because other than loading in 5 minutes late which was annoying and not helpful for my team, it wasn't that big of a deal. Recently, it has started to put me as AFK and not give me XP, mastery points, or LP, when it did before. I'm not really sure what the problem is, but some kind of explanation to why it happens or a fix would be helpful. I play on a 2015 21.5 inch iMac, which runs the actual game at around 100 fps, 30 ms.