Looks like its using YUI (a yahoo UI library) that was deprecated in 2011 in favor of YUI 3 (which is now deprecated as well). https://yui.github.io/yui2/docs/yui_2.5.0/docs/index.html

Im seeing a lighthouse mobile performance of 64 with Javascript execution time, unused js, legacy js on modern browsers, etc. as some of the top reasons.