oitsjustjose

Update:++ Disabling biome blending solved this, and reducing it reduced the spike. I still don't understand why lighting has any effect on biome blending  

I'd like to leave this alone, but the bug is even worse.

I'm using my MacBook with a 4K monitor. It's SENSELESS for the game to try to play it at 2x resolution (7680 x 4320) and playing in full screen isn't a good option. Changing fullscreen resolution makes alt-tabbing take forever because it's changing the screen resolution back, and doing some minimize effect. Plus if in macOS's fullscreen and choosing Minecraft's fullscreen option, the game crashes.

Essentially, I question if the implementation of 1.13 on macOS was ever tested... I'd love to play it, but it's just unreasonably difficult to do so.

Wouldn't be nearly as bad if it weren't for the AWFUL transition out of the game when alt-tabbing in Minecraft's fullscreen mode. The whole minimize thing is slow and distracting.

No worries then. I'll have a Forge ASM fix for this when 1.13 comes out and Forge accompanies it. Leave it to the modding community to fix the game like usual ¯_(ツ)_/¯ 

A: Just switched to the Vanilla launcher, same issue (no surprise) because it's an in-code issue.

B: If it changes the resolution to that high and Mojang is using it, they need to also utilize LWJGL's getPixelScaleFactor() instead of blatantly ignoring it - this is a new bug added since the LWJGL 3 update, and it needs to be addressed or else a large portion of the community playing on a Mac will have godawful performance.

No, it doesn't. My machine's max resolution is not 3360x2100, it's 2880x1800, so why on earth is the game playing at such a ridiculously high resolution? I don't even keep my scaling setting at that - it's meant to be scaled to look like 1680x1050. Attached is the Displays section of "About this Mac" 

Yes, but WHY. It makes no sense that it works one way but not the other, melons and pumpkins are exactly the same >.>