Why do you think Shakespeare inserts a comic scene at this point in the play?act 5 sc 1

As this play approaches its denouement, the emotional intensity becomes almost overwhelming.  Shakespeare understood that the audience needs a break at this point before the deaths of Gertrude, Claudius, Laertes, and Hamlet occur.  The playwright offers this comic relief just prior to Hamlet's and Horatio's witnessing the funeral of Ophelia in a scene that is at once poignant and anger-filled.  Laughter is the necessary outlet; this emotional discharge helps the audience prepare for the final, desperately tragic scene of the play.