Based on https://andydavies.me/blog/2018/09/06/safari-caching-and-3rd-party-resources/ https://andydavies.me/blog/2018/09/06/safari-caching-and-3rd... it seems

Based on https://andydavies.me/blog/2018/09/06/safari-caching-and-3rd-party-resources/ https://andydavies.me/blog/2018/09/06/safari-caching-and-3rd... it seems highly unlikely that a popular module will be in the cache - Safari double keys it's cache to prevent 3rd-parties tracking across sites - Usage of common libraries is just too low for their to be a critical mass A whole site running on a CDN still involves only one connection, will make use of the throughput growing the TCP congestion window grows, and a decent CDN is likely to be more reliable than the origin