Recently me and my friend started playing vanilla smp on a new world version 1.14.4, using the official server of the same version. However, every single time I (or he, doesnt matter, it appears only on users side) cross the certain chunks borders, from south to north, I have a lag and fps drop to zero. This makes the game literally unplayable. Don't write anything about RAM, hardware issues, wrong settings, optifine, whatever else, ip or connection, those all aspects are out of the question. Everything was good back then a couple of weeks ago on 1.14.2. Anyone experiencing same problems or knows how to fix it?
I'm having the exact same problem. I play on 1.14.4, single player, and when I cross from chunk 10, 5, -22 to 9, 5, -22 I get this awful lag spike. Crossing the other way does not lag, like in your video. Was absolutely fine on 1.14.2 but sadly now I can't downgrade my world.
Sorry I can't help, just wanted to let you know it's not just you. I'll let you know if I find a fix.
Edit: After a little further investigation, it happens if I re-create my world afresh with none of my building in it (the same chunks are affected) so it cannot be redstone-related. I notice you are on an amplified world. Mine is too. I re-created my world twice more but using the default and superflat types instead, and the problem was much reduced. Perhaps this is a problem that only affects aplified worlds? My investigation continues...