Sprinkler and nettle performance

OK play went to staccato when I built a water sprinkler. The console shows the "moisture listener" sampling the nettle vines at least a few times per second--catching only minuscule changes. I have nearly zero coding experience, but I do play a LOT of dwarf fortress, which runs into similar problems of polling statuses/data/effects in a ticks-per-second system. Limiting off-screen polling should help, or it may be better to sample once every five seconds, or assume:

If player.location > (sprinkler.location + 30)
  while sprinker.fuel > 0;
      radius = 3
      soakedArray = ([sprinkler.location]-radius, [sprinkler.location]+radius)
      for nettle in soakedArray
          nettle.wetness = 100 or TRUE
      wait 5000

Not sure if it's a bug, but if I remove a sprinkler with the command "TheInput:GetWorldEntityUnderMouse():Remove()", the sprinkler object and moisture listener disappear, but the water spraying animation and player wetness continue.