I believe you can buy speed, be it better fit, better suspension, better tyres.
But not all riders will notice “better”.
Some people I’ve ridden with don’t know if there tyres are pumped up, let alone what pressure.
Some inexperienced riders wont know how to make the most of a bike.
A lot of us only concentrate on our riding a tiny amount of time, not even the whole trail section, let alone the whole ride.
I’m a bit OCD on stuff and have gone out to session sections to get better, its bloody hard work physically and mentally. On any normal ride that just does not happen, so expecting a 5 second faster bike to be noticed on a normal ride will be an expectation missed.
However, it may make you feel faster – and if your not being measured by a competitor or stopwatch, feel is all you have.