How do you fix a lag on left for dead

Well there is no real way to fix lag on Left for Dead 1 or 2. The best thing you can do to battle lag is to have a good internet connection (not dial-up or a cheesy internet) and, if you're playing on the computer, to make sure your computer has the correct system requirements for the game. Unfortunately though, if you're playing online with someone that has a bad connection, it makes everyone playing with that person lag.