This issue has been reported in former snapshots of minecraft 1.14 but now,in normal 1.14(no optifine,no forge) it happened to me.I turned on chunk borders (F3+G) and noticed the frames were only skipping when i went trough the chunk grids. I tried everything i could think of like turning all my game settings to minimum or restarting minecraft or the pc.Nothing works so i suspect its a game related problem and not a pc related one.Ok,so i tested some stuff and this only happens on an amplified world in hardcore mode.Many thanks,Lolimator.I look forward to your response.