Why Does "Team Fortress 2" Lag So Much on My Computer?by Marie Cartwright
It does not matter what class you play; lag is the death of all Team Fortress 2 players. It can ruin the perfect sniper shot, the carefully planned back stab, the long-awaited UberCharge. Lag can strike at any time, but you can take steps to deduce why it's happening to you, and what you can do to prevent it.
Video Drivers and DirectX
As with any PC game, you need to make sure that all your drivers are up to date before running Team Fortress 2. Even though TF2 may not look like a graphics-heavy game, you want your video card running as smoothly as possible before you get online. You will also need to make sure your version of DirectX is up to date. Though version 8.1 is the minimum, DirectX 9 or higher is recommended for optimal performance.
When you are in the game, you've probably pressed the "Tab" key to get the scoreboard overlay. To the right of every player's score is his "Ping." Ping refers to how well a player is connected to the server, and how fast his data is being transmitted. The lower the Ping number, the better the connection. If you've got a high Ping, this indicates that your connection isn't moving as quickly as it should be. This is often the case if you are using a lower-speed Internet connection. High Ping can also be caused by geographic distance. If you are in the United States, and you are trying to connect to a server in Eastern Europe, your Ping is going to be much higher than if you were playing on a more local server.
The more people in the game, the heavier the burden on the server. Sometimes, there is not much you can do about lag in a high-population server. Using a fast Internet connection with a computer that has a high-speed processor will make you less susceptible to lag under these circumstances. If lag is a persistent problem on your server, you may want to try to find one with fewer players. In TF2, you want to avoid an empty map, but you also don't want to be too crowded.
Good Internet Habits
Online multiplayer games such as TF2 eat up a lot of bandwidth. Even if you've got a fast computer, having too many things running while you are playing can cause your game to lag. Avoid watching streaming video or listening to online music while you are in the middle of a match. Don't minimize the Steam window while a game is in progress. Exit instant messengers and voice chat programs.