San Francisco: Parag Agrawal has shaken up Twitter, including firing consumer product leader Kayvon Beykpour and head of revenue product Bruce Falck, as the micro-blogging platform gets ready for Elon Musk's $44 billion acquisition to close later this fall. In a memo sent to employees, Agrawal said there is a hiring freeze now and Twitter will also pause spending in most areas. "It's critical to have the right leaders at the right time. Jay Sullivan, currently interim GM of Bluebird, has shown this powerfully. I have, therefore, decided to make Jay the permanent GM of Bluebird," Agrawal said in the memo seen by The Verge. "Bluebird" is Twitter's consumer product team, and "Goldbird" is the team that builds revenue-generating products. "Staff" refers to Twitter's senior leadership team. Agrawal said that Beykpour will be leaving Twitter. "Under his leadership, our product has evolved and grown meaningfully... I know I speak for all of us when I say we are deeply grateful for his tremendous impact," said the Indian-origin CEO. Falck will be departing Twitter and "we will be opening the search for a new GM of Goldbird". "Under his leadership we rebuilt our ad server and anchored the foundation for evolving our ads business to be more performance based. In the interim, the Goldbird org reports to Jay Sullivan," said Agrawal.(/IANS) Effective this week, Twitter is pausing most hiring and backfills, except for business critical roles as determined by 'Staff' members.