LAG SPIKEEEEEEEES

Whats wrong can someone explain this to me?

First match when i turn on PC , then i open league client then i start a match first match i have 30ms !! second match i have 50 between 60ms unstable

third match 70ms but stable , then roll back.. on next matches never is the same? im 100% sure it Can't be my net , my net is 50mb speed download [slayer-jinx-unamused]

can someone give me solution to make it perma 30ms?