The high momentary reading in Internet traffic has nothing to do with the real Speed.
It is an artifact of the way the measure is done (using a short period of time for the averaging while the actual time is bigger, or having a momentary noise spike).
If 1000KB were downloaded in 1 sec. then the speed is 1MB/sec.
However if the 1000KB where erroneously divided by the application's software as though it is only .7 Sec. Then the "Speed" will say 1.4MB/sec. (Unlike people computer are Not perfect 😉 ).
Thus the real Speed is the one that appears in a Stable Download, and Not temporary measurement mistakes.
The so call "boost" offered by some ISPs has nothing to with the physical speed of the connection.
It is based on caching frequent revisited pages of sites by the user.
I.e., if you spend a lot of time on AT forums, the ISP "Boost will cache part of the forums so it appears quicker on your screen because it comes directly from the ISP's server instead of going all the way to AT's servers.
This "trick" makes cached pages appear faster but the actual line physical Speed is the same. Downloads or games' traffic that must come from the original server, as a result they will not "appear" faster, and would gain anything from the ""Boost"".
😎