my laptop slows down instantly after i connect to wireless

here's the story, i was playing League of
legend when suddenly the wireless gets
disconnected so i have to leave the game, but
when i quit my laptop freeze but i can mov th
cursor the screen just stop working so i push
the power button long enough to shut it
down.... after that i witch it back on and the
performance got so slow when connected to
internet, i cannot even make the task
manager open or right click the screen to
slect refresah because it won't pop up n
when i shut it down normally it just got stuck
aty wallpaper with no icon... when it is not
connected to internet from the start it works
fine which is weird... HEEELLLLPPPPPPP
my laptop is dell inspirion 7420