It takes me 5-10 minutes to load into a game

This year I've been having trouble loading into league games. Despite reaching 100% within two minutes on the loading screen, it takes me five to ten minutes to actually get into the game. This leads to me joining the game a bit late and throwing it for my team. It also has left me in a permanent state of leave buster. This issue occurs about every three games and I'm not sure how to fix it. When I finally get into games I have less than 90 ping usually. I'm not sure if this is related to my location (Hawaii and I use NA servers), my internet (which works fine for other games and tasks), or if it is because I play on a mac (which has worked fine for league for more than four years). Does anyone have any ideas of solutions? Any help is welcome and would be appreciated?

*Also, before someone criticizes me for playing on a mac, I did not have a choice in which computer I bought many years ago. My parents thought that only macs were good for school work since they're die hard apple users.