Use R ::= ZZ/(32003)[t,x,y,z], Lex;
  N := 31;
  I := Ideal(t^N+t^6+t-x, t^5-t-y, t^9-t-z);
  Set Timer;
Null
-------------------------------
  T := GBasis(I);
Cpu time = 2.88, User time = 30
-------------------------------

To time a single command, use 
    Time
  .  For example, above, we could
have written Time T := GBasis(I) instead of setting the timer.