The default debounce algorithm in QMK also introduces a minimum of 5ms delay, and the default usb polling rate another 10ms. To mitigate the debounce algorithm

The default debounce algorithm in QMK also introduces a minimum of 5ms delay, and the default usb polling rate another 10ms. To mitigate the debounce algorithm delay, you can put "DEBOUNCE_TYPE = asym_eager_defer_pk" in your rules.mk file. What this does: asym: use different debounce algorithm for key-down and key-up events. eager: the key-down is registered instantly at the first signal, instead of waiting 5ms for debounce defer: registering key-up will wait for the debounce delay, this will make sure you won't get multiple key-downs registered before a proper key-up pk: per key debounce timer, uses the most resource but you have plenty on your rp2040. although I don't completely understand how this works, this is supposed to be the fastest. To increase the polling rate, this can be defined in config.h: #define USB_POLLING_INTERVAL_MS 2 It's in ms, so 2 is 500hz, 1 is 1000hz, IMO the latter is overkill. Together, you save a minimum of 6ms, maximum of 14ms of delay, which is orders of magnitude more than you save by not scanning the matrix.