A system and method for the real-user capable monitoring of the rendering process of dynamically updated web pages is presented. The proposed approach deploys a browser agent to content loaded and displayed by a web browser which monitors resource load activities caused by the processing of the content by the browser and in-place content modifications caused by the executions of scripts and XHR communication by the browser. Those resource load and content modification activities affecting the visible area of the browser are identified and a point in time is calculated at which the visualization of the content for the visible area is complete. Further performance monitoring data describing the performance of the rendering process depending on the percentage of finished portions of the visible area over time is calculated. In addition, data describing the rendering process in detail may be captured by the browser agent which may be used for a later playback of the rendering process.