[CLIENT] Client lagging

So my client has been lagging for about a month. Its got to the point where in champion select, it takes about 5 seconds to register that I've selected my champ, and then fails to let me lock in, causing a dodge.

I'm writing this whilst waiting for a 30 minute leaver timer to expire.

It's not getting any better as this has happened twice this evening alone.

Fix please?

Very frustrating.

Ta