Cloud rendering has a considerable impact on performance as of 25w16a

As per 25w16a, clouds now appear all the way to the horizon. This means that changing the render distance will not affect cloud render distance and more clouds are now rendered compared to previous versions.

However, this does now have some side effects, because now that there’s not limit at which distance the clouds are visible, the game will now render clouds at a distance of up to 32 chunks, despite what the client has as the render distance value. Due to this, having clouds enabled now has a considerable impact on performance.

I’m reporting this because it seems like a valid performance concern and can affect players (notably on low end) that did make use of clouds before this change. If necessary, clouds can be turned off however.

How to reproduce

1. Open an instance of 1.21.5.

2. Create or open any world, preferably superflat.

3. Enable fancy clouds and set your render distance to any value, preferably below 12.

4. Enable F3+2 to see the frame graph and take a screenshot while looking at the horizon.

5. Close the game and reopen the world on an instance of 25w16a.

6. Repeat step 4 and compare the screenshots.