This document outlines an agenda for a meetup on Spark UDF performance. The meetup will include: an introduction of the speaker ([Guilherme Braccialli]); an overview of QuantumBlack, where the speaker works; a presentation on Spark UDF performance, including a live demo; conclusions about the performance of PySpark vs Scala UDFs; and time for questions. The speaker will share learnings from running Spark at scale and practical examples. He will conclude that PySpark Pandas UDFs can be faster than regular PySpark UDFs but not always, and that PySpark UDFs are slower than equivalent Scala UDFs. The speaker's approach is to use PySpark UDFs