I do do still have both computers set up side-by-side (legacy data from an old business), and the keyboard in question was a Microsoft Comfort Curve 2000 (the calculator button wasn't a proper key, it was one of those squidgy extra keys so beloved of multimedia keyboards, so not as fast to operate as a proper key.)
Anyhow, the point (arguably hypberbolic as it may have been) wasn't about reaction time per se, it was about the older calculator app - and by extension much of the rest of the OS - being a much simpler and less bloated piece of software, and running it on faster-than-contemporaneous hardware makes for a sense of immediacy which is sorely lacking in today's world of web apps.
I'd be very interested to know to what that 300ms "threshold of perceptible delay" applies. You might not notice a window taking 300ms to open - but I'd be willing to bet that when you're highlighting text with the mouse or dragging a slider, you'd be very aware of the UI lagging by nearly 1/3 of a second.
Since I still have the machine in question here, and I'm now interested enough to try and get some rough measurements, I've just videoed it with my phone (30fps video) and done some frame counting, both from a cold boot with nothing cached, and also a repeated launch.
Firstly from a cold boot:
It's hard to tell exactly when the keypress registers, but I believe what I'm seeing is the key being pressed, two frames later the hourglass appears, two frames after that the calculator appears. (The TFT screen will likely be adding at least one frame lag, but let's ignore that for now.) So that's somewhere between 166 and 200ms for a cold launch.
If I close the app and repeat, there's now just one frame between keypress and hourglass, and just one more frame between hourglass and the app appearing, so now nearer 100ms.
Looking at the videos my finger is off the key the first time the app appears, but not the second time - though if I made a special effort to release the key as quickly as possible I now think I could probably just about beat it.
But I think the question was the other way: Why couldn't calc.exe launch in 300ms?
Don't want to clutter too much, I'm already eating downvotes, so I'll link:
XP's calculator is hardly any different than 95. It's easy to believe that launching it on a Core 2 Duo of all things is also instant.
On the average consumer hardware at launch, 95 and XP were slow, memory hungry bloats. In fact everything that people say about Windows 11 now was even more true of Windows back then.
By the end of the life of Windows 95 and XP, hardware had overtook and Windows felt snappier.
There was a reason I stuck with Windows 2000 for years after the release of XP and it wasn’t because I was too cheep to buy XP.
Back in the day, we actually used to aim for that as a user experience metric.
Reactions are about responding to one off events.
Whereas what you’re describing is about perception of events aligned to a regular interval.
For example, I wouldn’t react to a game of whack-a-mole at 50ms, nor that quickly to a hazard while driving either. But I absolutely can tell you if synth isn’t quantised correctly by as little as 50ms.
Thats because the later isn’t a reaction. It’s a similar but different perception.
And for the music latency, you can here where the latency happens in relation to the rest of the music piece (be the rock music, techno, or whatever style of music). You have a point of reference. This makes latency less of a reaction event and more of a placement event. ie you're not just reacting to the latency, you're noticing the offset with the rest of the music. And that adds significant context to perception.
This is also ignores the point that musicians have to train themselves to hear this offset. It's like any advanced skill from a golf swing to writing code: it takes practice to get good at it.
So it's not the same. I can understand why people think it might be. But when you actually investigate this properly, you can see why DJs and musicians appear to have supernatural senses vs regular reaction times. It's because they're not actually all that equivalent.
You simply cannot use musicians as proof that people have these superhuman reaction times.