Re-using HTTPs connections is only helpful when you have repeat requests from the same user. It's actually counter productive for tracking beacons or ad impress

Re-using HTTPs connections is only helpful when you have repeat requests from the same user. It's actually counter productive for tracking beacons or ad impressions, where you rarely see the same user twice in rapid succession. For web applications the overhead is much less significant. Both because you can re-use connections, and because few web applications can manage 20k+ requests per second on low end hardware.