Hello, This is becoming an annoying issue, as internet lag in online games is fatal especially in games such as left 4 dead 2 and counter strike global offensive,
I don't have a bad router its the EE Fibre optic 60mb ping is usually fine around 30-40 in most servers but about every 10 mins or so, varies it climbs up to about 500 or so for about 30 or so seconds and goes back down,
My Specs are not that bad
I5 CPU Overclocked
Provided that there is nothing on your machine ...or anyone elses machine in your home network then you are seeing latency due to demand regardless if it is from your house or your neighbors on your ISP's feed or possibly the game server itself.