Facebook chat is designed to allow for real-time communication with your contacts, but this isn't what happens in certain instances. If you find that your chat frequently lags behind, whether the delay in messages you send to someone else or messages you receive from him, troubleshoot the issue to determine its root cause and to prevent it from happening again in the future.
Begin a chat with a different friend. Monitor both chats closely to see if similar delays occur in both. If only one shows a delay, the issue lies with the specific friend and not your Web browser or Internet connection.
Close out of your Web browser, which resets Java, the language in which Facebook chat is written -- and a delay in which sometimes causes chat lag. Reopen the browser, navigate to Facebook and start the chat anew. Alternatively, if Windows has recently prompted you to update Java, make sure and click "Yes" the next time it does.
Access Facebook using a different Internet connection if resetting Java doesn't eliminate chat lag and you can't narrow the problem to a specific friend. If messages you or others send appear later than you intend them to, a slow Internet connection -- the messages literally don't arrive until you see them -- is to blame.
Add Facebook Chat to a desktop chat client such as iChat or Pidgin to prevent all Web- and Java-related problems in the future. Open the "Accounts" section of the chat client, input your Facebook e-mail address and password, set the server as "chat.facebook.com" and the port as "5222," if the program requires one.