Game lag in single player like if i'm in multiplayer

Please attach a screenshot with the F3 screen open.

I hope this screenshot helps

The debug information doesn't show anything suspicious. Was your game lagging while you took these?

Yes this red line appear when the local server lag

is like when a connecion problem occurs, everything freezes for a second them get back to normal every 10-15 minutes

Just like before, I'm still getting block lag in 1.14 Pre2. I don't know if this is relevant, but if I break a block and I move onto breaking another block right away, when the first block finally falls to the ground it resets the progress I had breaking the 2nd one.

You need to identify the cause of the lag. Try to run a debug profiling when this happens (/debug start, /debug stop) and join the report located in the debug folder of your world folder. And after doing a profiling, read your logs (logs/latest.txt) to see if there is any line reporting that something took too long.

This issue is no longer happening on my end as of 1.14 Pre-Release 4. I haven't really checked the Pre-Release 3, but I guess that's irrelevant now.

I am also getting severe lag in singleplayer. It seems like the longer the world is open the worse it gets. Seems much worse for me anytime I enter or get near water. Still observing this on pre-release 5.

Please check if that's still an issue in 1.14.2.