"And in every province ... many lay in sackcloth and ashes." 4:3
Haman's wife and friends tell Haman to have a 25 meter high gallows be made to hang Mordecai on. So they did that in a single day.
The king couldn't sleep so he asked someone to read to him the book of Chronicles.
That ought to do it! 1 Chornicles is probably the most boring book ever written. No one can read
it without falling asleep. 6:1
The king had completely forgotten that he had ordered the genocide of the Jews back in chapter 3.
At Esther's request, the king orders a preemptive strike on all 127 provinces from Egypt to Ethiopia. Everyone who planned
to kill Jews shall be killed by Jews, along with their wives and children. And all this killing is to take place on a single day.
(How are the Jews to figure out who planned to kill them and who didn't? Were they supposed to just kill them all and let God sort it out?
And why did they need to kill the women and children?) 8:9-13
On the day when all Jew-haters (and their families) were killed by Jews, "the Jews had light, and gladness, and joy, and honour
... a feast and a good day." 8:16-17