LogicalGeekBoy

I'm seeing the same issue (see attached screenshot). Generally speaking the chunk loading is so much better, thank you! This test was done on a multiplayer server running 1.15-pre1. It's just a normal world, I changed to spectator mode and increased my speed a little, probably similar to elytra flight speed. I have my max FPS set to 120 and have a pretty good machine. As you can see from the screenshot, when I cross a chunk boundary there is a noticeable stutter. Thanks for the awesome work, 1.15 is shaping up very nicely!

I've seen the same behaviour and it seems to matter how many job sites there are and where they are. The villager seems to be able to find a workstation pretty quickly if they are all in the same chunk as they are but it takes a long time if they are not. I made a video showing this behaviour here: https://youtu.be/jyiJPvzvyEs There is a world download also here where you can easily recreate the issue: http://bit.ly/2MNUZLK.

This is an important bug to fix as many people (myself included) use the workstation blocks as decoration and having a lot of them in an area affects the gameplay in a negative way. I had to remove 2000 cauldrons that I was using as a ceiling decoration for example.

I hope that's useful <3

Logic

I've tested this and from what I've seen on my local machine piston rendering is much improved. However, ilmango shows in this video https://youtu.be/rSU4JNqaN34?t=153 an issue he experienced with flashing pistons in different chunks. I haven't observed this personally so it maybe locational?  

I'd just like to add that I've seen that message today and I think it's in error. I have an iMac (27-inch, Late 2013), NVIDIA GeForce GTX 775M 2048 MB. According to Apple here: https://support.apple.com/en-gb/HT202823, that card should support up to OpenGL 4.1. I hope that helps.

Confirmed in 1.13.2 and 1.14.2-pre1. If you run Optifine (1.13.2) with explosion animations turned off then this World Eater runs at normal FPS. It would be really good to fix the particle lag in general without the need for a client-side mod. Maybe at least an option to turn off particles all together rather than just the Minimal option that we currently have.

I've tested this in 1.14.2-pre1 and it seems to be fixed now. Thanks for the hard work! <3

I've added the world download and log file, hopefully that helps <3

I've done a follow up test and this behaviour is still the same in 1.14.1-pre1. Thanks for looking into it <3

I can confirm. I tested a mob farm in 1.13.2 and also in 1.14 and saw a 30% reduction in rates. This was confirmed by SciCraft code analysis which Gnembon mentioned in his video above. The change to the algorithm is related to pack-spawning. If any mob in the pack would spawn in a different chunk from the origin then the whole pack is aborted and hence the reduction in mob spawns generally.

As others have said the particle lag is incredible. I'm testing out a "World Eater" (https://drive.google.com/drive/folders/1Qbeydk87OdmJV3nkVHzN0_XGxnCc5Sr_ from this YouTube video: https://www.youtube.com/watch?v=I7BOA5Hl6yE) in 1.14 to see how it handles it. The good news is that it works but if I'm within render range of the TNT explosion particles then my frames drop to 1 FPS. 1.12 never had these issues, please spend some time on a 1.14.x release focused just on performance and please include a fix for this issue. Thanks <3

The general mouse scrolling does seem better in 1.14-pre2, thanks for the update there. However I am still not able to mouse wheel scroll the hotbar while sneaking. This was possible in 1.12.x, but since 1.13 to 1.14-pre2 this hasn't worked and is a bit frustrating while building when in a precarious position. Thanks.

I just wanted to confirm that I am seeing this issue too. I have a pumkin/melon farm from 1.12.2 and after upgrading to 1.13 the pumpkins/melons aren't growing anymore and there are farmland blocks directly above the stems (stacking style farm).  After some testing it seems that the crops grow if there is a transparent block such as glass or air above the stem but not if there is a partially transparent block such as farmland or slab. It seems to only matter what the first block directly above the stem is, so this isn't a sky access change.

I don't remember seeing this being mentioned as an intended change and so I'd personally class it as a bug. I hope that helps.

Additionally, I have also seen Ghast spawn on this platform in 1.13.1 but according to the wiki "Ghasts will not spawn in nether fortresses." (see https://minecraft.gamepedia.com/Ghast#Spawning)

So it would appear that 1.13.1 does not recognize this area as a fortress after upgrading from 1.12.2. I'm not sure if this affects all fortresses or just a subset.

Logic

I've had this exact issue. Here is what I did:

1. Create new world in 1.12.2

2. Built a prototype Wither Skeleton farm within the bounding box of a fortress - all mobs spawning as expected.

3. Upgraded the world to 1.13.1

4. No Blazes or Wither Skeletons are spawning on the platform only Pigmen and Enderman seen so far

I've attached the 1.12.2 and 1.13.1 worlds and screenshots. I looked at the Fortress.dat (using NBTExplorer) and it looks the same for both worlds so I assume the fortress is present in both but in 1.13.1 no fortress mobs spawn. You can see these platforms if you enter the nether and go to x=72, z=-299.

Yes, I understand how the breeders work. The issue here is the detection range of the villager has changed which breaks existing contraptions. If we want players to upgrade their world (which I assume we do) the upgrades should limit as much as possible changes that may affect existing builds. For a simple villager breeder then it's an easy fix but for some of the non-trivial iron farms this is a big problem. I would say, unless there is a good reason for changing this mechanic then it it should be kept as it is in 1.12.