so, i decided to play with redstone again in modded minecraft, and as i was building a binary decoder, i noticed a odd flickering... gates flickered off and on at odd timing (such as between clock cycles) and generally looked odd... but function wise they worked without trouble.
since it was graphics wise, it didt take long to find that optifine was the culprit. removing it indeed gets rid of the flickering, but the lag is immense then... i got quite a beefy computer, but even a simple decoder like this makes it lose a few frames, let alone if i build the rest of the system... so i have to have optifine, but this bug makes debugging my circuits very unpleasant.
i already tried toying with all the setting. turning everything off or on does not impact it in the slightest. i tried going to the earliest version of optifine compatible with 1.12.2 but it had the same issues too.
does anyone have a clue what it could be? usually this was a sign that optifine multicore rendering was screwing up, but this option is nowhere to be found. i made a video displaying the odd behaviour. within it, it can be seen that it even affects gates upstream, which should not even recieve a signal change at all! it also seems that its chunk based, since turning on a different lever only makes a few of the gates flicker, further suggesting its optifine's multicore rendering shenanigans...
any clue how to stop optifine from doing that without removing it? :c
EDIT: so, i found another mod called VanillaFix, which also gets rid of the lag, but then shows the exact same behaviour, so this is bigger than optifine itself.
EDIT EDIT: a mod called Foamfix also shows the exact same behaviour... it must be whatever fix they apply to get rid of the lag also causes this issue... and none of their settings affect the results