I noticed lag on macOS and I have some handwavey solution for it...

[alexgu754]

out_foo.webm

You have to use 'CVDisplayLink', record your command buffer there and call [commandBuffer presentDrawable:view.currentDrawable atTime: hostTimeSeconds];, using the 'const CVTimeStamp* outputTime' from the CVDisplayLink argument. Otherwise you get absolutely horrendous frame lag. anyone with a mac can open any bgfx demo and try resizing an imgui window and see for themselves, the mouse is like 5 frames behind

[mcourteaux]

Interesting! You should make a PR that implements the fix you demonstrate.

[bkaradzic]

Lag you're noticing is between hardware mouse, and rendered UI. Common solution for this is to when dragging rendered items turn off hardware mouse, and turn on software mouse that sticks to rendered UI. If you use Chrome Browser you could see this if you're using some program that adjust display color temperature according to location and time of day (f.lux or redeye for example), because hardware cursor is unaffected by this color shift change, and software cursor is not, so cursor color changes once switch between hardware and software cursor happens.

[alexgu754]

sure, so that's one solution to mask the lag with a custom rendered mouse. But you can eliminate it all together practically, using the conventional way apple wants you to structure your program with your rendering done in -(void)drawInMTKView:(MTKView*)
(although if you run at 60 fps and don't skip a frame, vsync seems to forcibly slow you down, I guess that means to many frames get queued)

2025-11-23.07-52-56.mp4

and I don't think that's what chrome does, https://www.w3schools.com/howto/howto_js_draggable.asp I think chrome is just literally well implemented and doesn't have this problem.

so if you just have a conventional game while loop with while(!quit) { sample_input(); render(); }
you're going to have this software hardware mouse lag on mac. unless you use CVDisplayLink to tell your main thread to wake up, although it's kind of broken when minimising your window and has been depreciated actually

[alexgu754]

sliderrr.webm
ok, I think I get it now. fixed the issue where it wasn't working after minimising / turning off the link and its pr worthy

[alexgu754]

Ok I tried changing renderer_mtl.mm and there were random frame drops for some reason and I honestly don't want to invest more time into this, maybe drawables were being discarded without doing the drawn callback, and I'm not using bgfx anymore so its no benefit to me
I made this repo for reference for what it should be that uses sdl3
https://github.com/alexgu754/LowLatencyOSX/tree/main