Lag Spikes

Since this last patch I've had horrendous lag spikes, everything starts out ok at between 38-40ms and then as the game starts going for no apparent reason in the middle of nothing in particular it just spikes up to around 300-600ms and I can clearly tell when this is happening because none of my clicks will register for a good 2 seconds after clicking. I've run all the diagnostics and it's not on my end, it's 100% riot serverside issues. The interesting thing is the FPS stays at over 100 while this is going on. So it's not a video issue.