Sorry, the pics are a bit later than promised (revenge!!). The issue with the Frost Moon arena is the number of pumpkins generated by the Horseman's Blade; I've run the farm during the day with the Solar Eruption and there was no lag. @Cyberra the rail is around 100 tiles away from the chamber, if you're going to use this set up. Although it looks like only red wire going into the chamber, it's actually all three; the colours seem to have display priority over each other, instead of appearing mixed.
The issue with the Truffle Worm farm is the flame traps; I know this because my life fruit farm used to have them (to clear the vines) and it lagged just as badly. I've since switched that one to dart traps and there is now no lag.
Both these issues began with the last patch, not the original update to 1.3.
Neat. I have no idea how to build it, though... Is that one of those "hoik" things? I've heard of them but have no clue whatsoever how to build them or make them work. I'd need a video with a step-by-step building and wiring guide, something no builder on YT seems to make, or someone with a lot more brains than me to build it for me.
Getting someone in to build it for me would also require the devs to actually fix the multiplayer tally counter reset issue, since I am not losing all my rare-banner progress again. Or building it in one of my secondary worlds.