Assuming the server is not lagging. Your connection is slow or congested, your bnc host is slow or congested, your routing to your bnc or your bnc's routing to the server is generally bad (in which case i suggest a change of bnc host).
The server will perform the kick command as soon as it recieves the request to do so, there is no slow or fast version. Note: your lag to the server will not only cause your kick commands to take longer, but it will cause all other events for other users (such as kicks) to seem to take longer.
