WizzBangWA

Experiencing horrible tps issues here as well.  New world as of 1.13.  When 2 people are on the server, no problem.  As more people join, tps drops.  We currently have 7 people on, tps is at 10.  On 1.12.2, 7 people wouldn't hit tps at all.  We tried a different node on our provider using a backup server, tps was the same on a new 1.13.1 world as our primary 1.13 world.  Switched our secondary server to 1.12.2, same seed, everyone spread out to their base locations, tps is fine, even with the world generating.

@Xitomati

You're assuming I know anything about minecraft commands.  How about sharing the process you use and the commands you use?  Are you on a local world, or a sever world?  I'm using a server world.  Local world generation might be fine, server world generation might not be.

I restarted the world and cleared levels 1-20 of everything but ore in the same chunks I mined in.  It's amazing, there's actually ore generated.  I did the same on a backup of the previous world, pretty baron.  Used the same seed on 1.12.2, ore generation looks to be identical to the current world.  I may or may not have hit a fluke.  For those wondering, I used the fill command to replace blocks with air.

Not fixed, at least for me.  Been mining on a new world that is the same seed as our 18w-pre4 seed.  Been mining for two hours.  Previous world I had plenty of iron, more coal than what I know what to do with, plenty of redstone, barely any lapis, 10 gold, 42 diamonds. We recreated the world in pre5 for the supposedly fixed ore generation.  Same amount of mining in the exact same area yielded 25 iron ingots, 2 stacks of coal, 0 diamonds, 2 stacks of redstone, 0 gold, 0 lapis.  I have been lighting up caves at 15 and lower, the ore is pretty slim pickings for iron and coal.  Redstone seems to be ok.  The rest of the ores haven't generated at all.