From 6.2 to 0.15 seconds – an Industrial Case Study on Mobile Web Performance

Background. A fast loading web app can be a key success factor in terms of user experience. However, improving the performance of a web app is not trivial and requires a deep understanding of both the browser engine and the specific usage scenarios of the web app under consideration. Aims. This paper presents an industrial case study targeting a large web-based dashboard, where its performance was improved via 13 distinct interventions over a four-month period. Method. Firstly, we design a replicable performance engineering plan, where the technical realization of each intervention is reported in details together with its development effort. Secondly, we develop a benchmarking tool which supports 11 widely-used web performance metrics. Finally, we use the benchmarking tool to quantitatively evaluate the performance of the target web app. Results. We observe a considerable performance improvement over the course of the 13 interventions. Among others, we achieve a 97.56% reduction of the time for the First Contentful Paint (i.e., from 6.29 to 0.15 seconds) and a 19.85% improvement of the Speed Index metric (i.e., from 15.31 to 12.27 seconds). Conclusions. This case study shows the value of a continuous focus on performance engineering in the context of large-scale web apps. Moreover, we recommend developers to carefully plan their performance engineering activities since different interventions require different efforts and can have very different effects on the overall performance of the system.