Minecraft 15w47c, Minecraft 15w49a, Minecraft 15w49b, Minecraft 16w05b, Minecraft 16w06a, Minecraft 1.9 Pre-Release 1, Minecraft 1.9 Pre-Release 2, Minecraft 1.10.2, Minecraft 16w32a, Minecraft 16w32b, Minecraft 1.12.1, Minecraft 1.12.2, Minecraft 1.13.1, 1.15.2, 1.16 Release Candidate 1, 1.16, 1.16.2 Pre-release 1, 20w46a, 21w03a, 1.16.5, 21w05b, 21w06a, 21w07a, 21w08b, 1.17, 1.17.1 Pre-release 1, 1.17.1, 21w40a, 1.18.1, 1.18.2, 22w18a, 1.19.2, 1.19.3 Release Candidate 3, 1.19.3, 23w03a
If you bump up the randomTickSpeed to a high number, it does not speed up the process of cauldrons being filled by rain.
Rain is on, a grid of cauldrons been placed, not snowing, not a desert.
randomTickSpeed = 3: slow filling.
randomTickSpeed = 3000: fast filling
randomTickSpeed does not affect it at all
it would make sense cause it randomly fills the cauldrons the way crops grow.