Why is my online game so slow? And how can we reduce lag?

Slow computer game
A game's online performance can be attributed to many factors. Below is a list of some common causes of why an online game may be slow or laggy.

Connection speed
If you're using a dial-up modem to connect and play online games, you are going to notice a much higher ping than others who have a broadband connection. If you do have broadband and are still experiencing lag, test your Internet connection to see what your throughput is.

How to test the speed of your Internet connection.
Testing your connection speed helps determine if the issues are caused by the Internet or server connection.

Server
The server location, its connection type and speed, and how many players are currently using it, all affect the gaming experience. Below are a few recommendations to try.

See if all users are experiencing high pings or high latency. Often if all users are slow it's likely the server has too many players for the connection being used.
Try an alternate server. Servers can be located anywhere in the world and if the server you're playing on is in another country it affects your connection speed.
Play the game at a different time of day. If the game's server is being utilized for more multiple titles or other tasks it could be currently experiencing a heavy work load, which lowers performance.
Updates
Verify you have the latest updates for your game and the operating system you're using to play the games. Often updating the game to the latest version, updating the hardware drivers, and updating the operating system can improve a game's performance offline and online.

More complex environment
When entering an area with other players, the computer's frames decrease due to the resources needed to load each of the characters and their actions. If your computer's performance decreases when there are other players on your screen, reduce the game's video quality through the game's "Settings" or "Display Settings."