What plugins are you running? Also, by everything else is smooth, how sure are you of that? Chat lag may be the only thing you've noticed lagging.
Get command book from Bukkit dev. The following will help determine if it's network lag or it your computer. Type: /debug clock If it returns excellent then you have network lag. If it returns 'clock behind', then it's your processor. In this case, close some processes or get a better CPU. However if you have network lag it is no doubt due to your Internet upload speed being poor. There's nothing you can really do about this if you live in the UK, as most ISPs don't do Internet upgrades unless they are paid for it. Even then they moan and delay, so it can sometimes take months - at your expense. Your best option would be to buy a dedicated server, however most people can't afford it. Try a plugin such as NoLagg.
RROD NoLagg is lagging my server RROD I got 1.2 mbps upload speed some master servers says I can host 1-12 players and I got AMD Dual Core too FIXED NOW FOR 9-10 PLAYERS SOME PEOPLE LAGS DUE TO FAR AWAY FROM THE SERVER EDIT by Moderator: merged posts, please use the edit button instead of double posting.
RROD Thanks mate RROD I also get an excellent thing on command book [Debug Clock] Do you know any plugin that does that too except Command book cause I have Essentials EDIT by Moderator: merged posts, please use the edit button instead of double posting.
RROD I'll give you my essentials file and can you convert it to CommandBook cause I'm having a bad time with it
You can't convert one plugin to another, lol! Just delete Essentials and replace it with CmdBook. Then, follow the permission configuration found on the same link.