The new feature of histograms and percentiles brings a more detailed view of web application performance by providing the ability to see response times at different levels, including averages, histograms, and percentiles. This allows developers to identify outliers and pinpoint specific transactions causing poor performance, enabling them to make data-driven decisions to optimize their application's performance. The feature is now available for all customers, with histograms and percentiles being free and accessible on both individual web transactions and overview pages.