I personally do not trust speedtest, if you like to see actual throughput - make actual throughput. Run a torrent client and download several popular torrents, so that there are good number of peers. You will get proper load on device as there will be many connection entries in conntrack, as there are many remote sources/destinations your bottleneck will be your uplink or your router.
Problem with http traffic - it looks like DNS or change-mss problem.
With great knowledge comes great responsibility, because of ability to recognize id... incompetent people much faster.