"Wisely, and slow, they stumble that run fast" says Friar Laurence to Romeo at the end of their first scene together. And he has a point. There are lots of instances of haste, and moments where time feels tightly compressed in the play. For example
- Capulet only sends out the invitations to his party on the day - the party is on that night!
- Paris, for some reason, has been invited to the party that night, and Lady Capulet seems already to know that he wants to marry Juliet. It's all happening fast.
- Romeo meets Juliet at a party, and falls immediately in love with her. That night he agrees to marry her at her window.
- He doesn't sleep, but goes straight to Friar Laurence, who agrees to marry them that same day.
- Moments after Mercutio is killed, Romeo instantaneously decides to challenge Tybalt. He kills him.
- It is that same night, it seems, that Capulet agrees that Juliet will marry Paris on Thursday. As Friar Laurence says, "the time is very short".
- When Juliet relents to her father, he brings the marriage forward a day, to Wednesday.
- Juliet fakes her own death on Tuesday night, and is taken to the vault on Wednesday. Romeo arrives, finds her dead, and without hesitation, kills himself. She awakes, finds his body and kills herself.
The plot -as you can see - depends on haste. The above looks like a summary: it is, in fact, a list of the quick and fast actions.
Hope it helps!