What is SpaceFN and why you should give it a try
The SpaceFN concept - setting up your space key as a layer switch when held - is probably one of the most useful tweaks in the keyboard hobby. Let me explain how it works. My SpaceFN article on kbd.news made some rounds recently - quite surprisingly given the age of this concept. This piece you're reading is a condensed version of the full post. If you're left with unanswered questions, you'll most likely find the info you're looking for in the original write-up. On my imaginary top list of the most useful keyboard features, tweaks and hacks, SpaceFN would deserve a podium finish for sure. But what makes it so special? In short: SpaceFN is easy to implement, easy to learn, costs nothing, can be used with any keyboard, and can improve your productivity instantly. I will list its benefits below, but can state right at this point that the SpaceFN concept, setting up your space key as a layer switch when held, is clearly one of the most useful tweaks in the keyboard hobby....
Apr 30, 2024
TL;DR: The keyboard seems to report at 125Hz-200Hz at 6KRO mode, or 1000Hz at NKRO mode. The CTRL starts up at 6KRO mode by default for Mac compatibility, so make sure it's at NKRO if you're on Windows. (I use this key rollover test -- http://gadzikowski.com/nkeyrollover.html -- and mash-hold 8+ keys)
One going theory for a lower polling rate is debounce prevention, where the keyboard tries to prevent a switch occasionally rattling on the contacts from counting as multiple presses. I switched it off and didn't see a difference in polling rate that couldn't be explained by NKRO. (see below) It might actually mean added lag for up to the set debounce time (in this case 5 cycles = ~5-6ms), but I have no reason to believe "gaming" keyboards don't do debouncing as well.
I then played with 6KRO (6-key rollover) & NKRO (n-key rollover) and noticed that 6KRO caps out at around ~140-170Hz -- similar to what DarkMio said re: Mac and 6KRO -- but NKRO reaches several hundred Hz. If I tweak my (horrible) way of testing to 4 numpad directions "at once" 6KRO stays around that range but NKRO regularly hovers around 600-1000Hz, matching what you'd see on gaming keyboards with this method. (reported 800-1000Hz)
Take this with a grain of salt, but this seems to match up with other people's tests of 125Hz and 1000Hz keyboards. (See here: https://geekhack.org/index.php?topic=61607.msg1431368#msg1431368 )
This should give stable results.