loading screen not freeze but still stuck at 84 %

I just don't understand, recently (almost a week ) , I can't properly join a game. i explain myself. select champ good, selecting rune, good. Black screen and then the loading appears and the percentage rise immediately to 84 % and didn't move for like 5 min. AND if I'm lucky enough, I can join the game but with 5 min or 10 min LATE . so , If i'm not report for AFK , i can't even fight back because they are already above me . i'm lost and seek for help . CAn someone help me ?

PS : nothing is running behind , no music and no others applications [zombie-nunu-bummed]