An Empirical Study on the Impact of CSS Prefixes on the Energy Consumption and Performance of Mobile Web Apps

Context. Many mobile web apps are using CSS vendor prefixes today. The presence of CSS prefixes might impact the energy consumption and performance of mobile web apps. Goal. The goal of this research is to empirically assess the impact of using CSS prefixes on the energy consumption and performance of mobile web apps. Method. To assess the impact of CSS prefixes, we mine 25 real mobile web apps and create two variants for each of them, one with CSS prefixes and one without them. Then, we load the mobile web apps on two Android devices across three different browsers (i.e., Google Chrome, Mozilla Firefox, and Opera). For each run of the experiment, we measure the energy consumption, page load time, and CPU usage of the targeted browser. Results. CSS prefixes do not lead to an observable impact on the energy consumption of the measured Web apps, while their absence leads to a statistically significant increase of CPU usage in all browsers. The presence of CSS prefixes has a statistically significant negative impact on the loading time in all browsers and devices. Conclusions. Assuming that the targeted mobile web app loads properly without CSS prefixes, we advise web developers to remove CSS prefixes if their goal is to reduce page load time. We collect and discuss strategies about how to safely remove CSS prefixes without incurring compatibility issues. The choice of whether to use CSS vendor prefixes should be made with consideration of the targeted devices and browsers, especially when dealing with energy consumption and CPU usage.