Slow is the new downtime` highlights the nuances of measuring slow performance, which differs from traditional downtime. The concept of slow has no standard definition and can vary across users, making debugging challenging. Google's recent release of Web Vitals provides a uniform definition of slow, with a threshold metric called p75(LCP) over 4 seconds, indicating that 75% of transactions meet this time threshold. However, without real-time intelligence about specific users experiencing slow, simply relying on Web Vitals may not be enough to address performance issues. Performance's Web Vital histograms and custom queries can help identify slow transactions and provide insights into user experiences, enabling developers to make data-driven decisions and fix slow issues more effectively.