Edit: even with the non flash test I can't do a speedtest without hitting 100% CPU on a core w/ a Core i7 CPU (not a celeron). It's actually [censored] difficult to saturate a 1gig/sec link even on a LAN, nevermind to a speedtest server with some very questionable javascript.
Aha, but thinking outside of la bo�te - take my 5 person family, each with their own PC's, smartphones, Xboxes, smart TV's, YouView boxes.
Line up 5 comparable PC's, set each of them running said speedtest in parallel, combine the results. Granted, you are probably more than likely to move the restriction from the PC equipment to the hub/switch , router/modem.
Whilst my nice new shiny FTTC connection here in this village is great because my download/upload speeds are a tadge better than the 1.5meg / 200k ADSL I had back in August 2013, by far the biggest benefit is not being impacted by what anyone else is doing in the house.
It means not having to schedule my S3/Glacier transfers/backups during the midnight hours, they can run 3 or 6 hourly. Or it allows me to stream BBC News (or sport) on 2nd monitor whilst having to work away on a problem on the other, without impacting #1 son on Xbox, #2 son on Netflix, #1 daughter on Spotify, wife on YouView etc etc.
No more "stop what you are doing for an hour whist I download this latest patch/upgrade/software/video, ok, who's next for the connection".
Twas like having 5 people, one bathroom and always a big queue at certain times.
You give my kids a 1Gigabit connection and they will show me how to use it
but... I do get your point... 100/100 or even 100/20 is probably fine. 330/30 is probably better/enough