Improving JavaScript performance via efficient in-memory bytecode caching

Web browsing is one of the most important applications for personalized consumer electronics devices such as smartphones and tablets. It is common usage pattern on these devices for a user to visit a relatively small set of websites repeatedly, which dominates the total browsing time. Exploiting this, modern web browsers cache downloaded resources in local disks such as HTML/JavaScript files and image files. While saving network bandwidth, resource caching does not eliminate redundant computation for processing these files. This paper presents an efficient in-memory code cache to improve the performance of interactive, dynamic webpages written in JavaScript. Evaluated on a production-grade JavaScript engine with JSBench, which record-and-replays five real-world websites, the proposed technique reduces both JavaScript compilation time and execution time by 57.9% and 30.9% on an embedded platform running at 2.3 GHz with 2GB RAM.