Code coverage shows what lines or branches your tests are missing. If you maintain Python code, chances are you use coverage.py to measure it. You probably don't use it all the time, though, as it slows down your tests -- up to a whopping 2.6x. This talk introduces SlipCover, a new tool that brings this overhead down to only 5%. We look into what slows down coverage.py, and show how SlipCover is able to do better. For Python 3.12, SlipCover adopts the new Low Impact Monitoring API (PEP669); we discuss the advantages and challenges of integrating it into SlipCover. Slides: https://pycon-assets.s3.amazonaws.com/2024/media/presentation_slides/110/2024-05-14T18%3A33%3A26.308459/SlipCover-PyCon24.pdf