It is not uncommon for an overloaded IRC server to be slow to echo what users are typing in a channel.
Sometimes your messages may seem to take a long time to be echoed by the IRC server back to your screen, and other users may seem to take an extra long time to answer you. If so, you may be experiencing network lag on an overloaded server.
The only thing you can do to minimize network lag is choose a server that is close to you on the Internet so you will speed up your connection as much as possible. You can connect to several servers, even several servers on the same network, sign on to a common channel such as #newbies, and then check the typical delays on that network with the IRC ping command.