DuckCorp Dico

Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   lag
    n.
       [MUD, IRC; very common] When used without qualification this is synonymous
       with netlag. Curiously, people will often complain “I'm really lagged”
       when in fact it is their server or network connection that is lagging.