It is only 20% at certain tasks, not all around and depends on what the specific bottlenecks are for a given workflow. I'm not saying it's bad, but not enough to fork over a few thousand every year to upgrade. In 1992 a 496 DX2 @66mhz was king... In 2000 (8 years later) there were Intel and AMD at over 1Ghz. By 2008 you had 4 cores, 8 threads at 3.2Ghz.
I used to upgrade about every year or two, there were massive gains... now, I'll hold out 3-5 years and not even think twice about it.
It’s a bit crazy to compare such massive time differences apart though isn’t it.
Also, who ok their right mind gets a new computer every year? No one (sane / without a giant disposable income) even gets a new phone every year anymore.
I used to upgrade about every year or two, there were massive gains... now, I'll hold out 3-5 years and not even think twice about it.