The bug
The average ticks per second in the latest pre-release is lower than usual. Old worlds as well as new worlds are affected. This was not an issue in 1.13-pre4.
This can be reproduced by using /debug
or lighting TNT and observing the delay for it to explode. Eating food also takes a while.
Linked issues
is duplicated by
Attachments
Comments

Happens to me too.
It seems like the further away you are the longer it takes to explode.

Generating chunks has always been an intensive process. It takes more time for the server to process more events with chunk generation.
I'm getting about 10-15 TPS on a world that has nothing going on. I'm pretty sure this is a bug, an a huge bug as well.
Despite what Matthew is claiming, i have noticed quite poor performance with pre5 as apposed to any of the other pre's and thats noticeable with only a few people online and when you get to 20 odd users, the screaming of lag is quite real. And with majority of users on my server all ready having a base and nether and the end being quite explored for the size of the map we have, its certainly nothing to do with new chunk generation.
Someone really needs to be assigned to this because this issue is game breaking and will affect a lot of servers.
I was about to open a ticket, but I think what I saw might be related. When eating, the animation finishes before the game counts the food as being consumed. It takes about another second after the animation for it to take affect.
TPS at 15 on a superflat world... :/

Do you have a cause for this issue? Saying that there is bad TPS gives Mojang nothing to go on towards fixing this issue.
Also, can confirm some TPS issues.
I attached a gif showing eating food. The first time I release the mouse button after the animation. The second time I continue to hold it.

Sounds like a duplicate of MC-131614
We could also add the debug text file so they can see what is causing all the lag.
I don't think it's a duplicate of MC-131614
The server admin checked the logs and there were no errors or warnings. The server is acting just fine, it's just running at ~15 TPS.

There is an indubitable TPS bug in this pre-release. I've been getting ~16TPS in empty superflat worlds while having my render distance set to 17. When setting my render distance to two, I receive ~18.5TPS. A friend of mine tested their TPS in a superflat world and got similar results. When in one of my maps – which utilizes mainly functions for mechanics – I get 6TPS on average; this would run at 20TPS beforehand. This didn't seem to occur during any of the previous pre-releases.
I'm observing this on my server. Food is taking a moment longer than it should to eat, and I've noticed some laggy feelings in general. The server is not complaining about being unable to keep up.

Jakob Knigga,
The server won't spit out those messages unless the debug mode is on. Using /debug start you can see processes that are taking too long and overloading the server (/debug stop to generate a report and see tickrate). The server isn't acting fine when it is running 25% slower than usual consistently.

I did some further testing by comparing the debug profiler results of the same world in pre-release 4 and pre-release 5 under similar conditions for about two minutes. It looks as if there is nothing out of the ordinary that is causing an extreme amount of lag.
[media]I'm experiencing this issue too. The server is just running slower than it should, and it's messing up the timings of everything. No client lag at all.
@Matthew Hunter - I was using debug mode. Either way, your post comparing the two pre-releases is exactly the problem. Nothing is lagging, the TPS is just lower.
Seeing the same thing here. No lag on client side. Server runs at very low tick rate. Eating takes a long time. Mobs move slowly and jittery. None of the usual suspects seem to be at play in this world (no redstone or other mechanical contraptions). The lag started to occur shortly after switching from 1.13-pre4 to 1.13-pre5.
Also experiencing this. Thought it was weird when I saw pufferfish jolting forward. Checked out other mobs, same thing. Ran /debug, and now running 9-10 TPS, when I was hitting 19+ before (server is nearing completion, so no other players on atm).
Nothing has changed on my end, except upgrading to pre-5. Client side, everything seems fine except for eating food, and seeing mobs move slowly.
Also, restarted the server to clear up any issues that may have caused. Was at 9 TPS the moment I logged on.
This is again in 18w33a.
and 1.13.1-pre1
This is happening because your server is running at a slower tickrate.