The performance of user-facing applications is critical to client platforms. Many of these applications are event-driven and exhibit “bursty” behavior: the application is generally idle but generates bursts of activity in response to human interaction. We study one example of a bursty application, web-browsers, and produce two important insights: (1) Activity bursts contain false parallelism, bringing many cores out of a deep sleep to inefficiently render a single webpage, and (2) these bursts are highly compute driven, and thus scale nearly linearly with frequency. We show average performance gains/energy reductions of 14%/17% respectively on real hardware by statically moving threads from multiple cores to a single core. We then propose dynamic hardware driven thread migration and scheduling enhancements that detect these bursts, leading to further benefits.