By testing my SSW in the 1.14 I noticed that my gold farm (Design from https://youtu.be/l9oteFEj770) caused more lag than in the previous version 1.13.2
I gathered a standalone copy of the farm and debugged it.
How to reproduce:
Do the following steps for each version 1.13.2 and 1.14
Download the attached world and paste it into your saves
Optimize and join the world
Get yourself some snowballs
Fly to the upper edge of the glass box in the center and land there
Update your gamemode to survival
Start debugging with: debug start
Now activate the farm (Video example: https://youtu.be/bIOKkBAnAKU?t=40)
Throw a snowball against a zombie pigman
Jump fast down onto the highest trapdoor
Wait a minute while the pigman are running towards you, then die and respawn
Stop debugging: debug stop
Results (see attached files)
1.13.2 [06] | | | | | | minecraft:iron_golem - 8.09%/7.14%
1.14[07] | | | | | | | minecraft:iron_golem - 31.82%/11.52%
In 1.14 the debug root value changed from[00] levels - 98.72%/98.72%
to[01] | levels - 99.03%/40.54%
(I don't know if this is intended or must be considered)
If you consider it, you get a total value of 11.52% / 40.54% * 100% = ~30%
from the total server performance. This represents an increase by 4x.
Nevertheless the pathfinding seems to use unexpected much performance:
1.14[12] | | | | | | | | | | | | pathfind - 96.67%/8.01%
1.13.2[11] | | | | | | | | | | | pathfind - 82.80%/0.50%
Because of the fact that the golems are staying on a 1x1 block and are completely surrounded by a gap they definetly can't pass I would expect a much lower value in 1.14.
As MC-182325 has been fixed, this should be no longer of an issue for you. Please check if this still affects you in 1.16-pre6 or later.