The problem with '100M' is that many websites do not go that fast... :/
Even youtube limits its bandwidth to stop fast guys hogging it away from others!
Fast.com gives me a 'real speed' of about 80M, but speedtests give my 'headline speed' of around 150M..
EG most motorways you can go at 100 MPH, BUT ONLY if there is NO traffic!
with normal traffic, the speed is much less...