heavyweight

heavyweight adj.  High-overhead; {baroque};
   code-intensive; featureful, but costly.  Esp. used of
   communication protocols, language designs, and any sort of
   implementation in which maximum generality and/or ease of
   implementation has been pushed at the expense of mundane
   considerations such as speed, memory utilization, and startup time.
   {EMACS} is a heavyweight editor; {X} is an *extremely*
   heavyweight window system.  This term isn't pejorative, but one
   hacker's heavyweight is another's {elephantine} and a third's
   {monstrosity}.  Oppose `lightweight'.  Usage: now borders on
   techspeak, especially in the compound `heavyweight process'.