Cauldron models are very unoptimized, causing render lag

The bug

Cauldrons are perhaps one of the most complex block models in vanilla Minecraft, using 58 texture planes. We can therefore expect pretty much any situation which uses a lot of cauldrons, such as an automatic dripstone lava farm, to cause quite a significant amount of rendering lag due to having to render several tens of planes per cauldron. We, however, can do better.

Attached to this ticket is a resource pack which perfectly recreates the vanilla cauldron (and I've thoroughly tested this to be sure; there are no visual differences unless you clip inside of the cauldron) using just 46 texture planes instead, cutting out 12 unneccessary texture planes. This resource pack also fixes the three cauldrons containing a fluid level (adding in one extra plane to fix MC-205095).

It would be possible to optimize cauldrons even further using an approach described in MC-262427 and also utilized in MC-262452. However, due to MC-262462, this cannot currently be done.

How to reproduce

Refer to MC-262427, MC-262452 and/or MC-262461 and extrapolate.

How to fix

Replace the "cauldron.json", "template_cauldron_level1.json", "template_cauldron_level2.json" and "template_cauldron_full.json" files currently in Minecraft with the model files in the resource pack. Mojang have my full permission to use these optimized model files. Optimization is always a good thing.