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The Performance and Overlays page
By Ryleigh Newman · Published
The Performance and Overlays page in Rockstar Shaders is where frames are traded for pixels, and where the overlays that show what a frame costs live. Its twelve settings cover the overlays, the zoom key, leaf culling, Render scale, Target FPS and two MetalFX switches. The one that matters most is Render scale: at 1706x1966 on my M4 Max, 75% took the frame from 44.98 to 33.95 ms, while each quality slider one step down was worth a few tenths of a millisecond. That is why 75% is the default.
I made Rockstar Shaders, and every number on this page was measured on one machine, an Apple M4 Max with 48 GB, at the resolution named beside it. A frame time is only comparable at the resolution it was taken at, so read these as the shape of the cost, not a promise for your Mac.
Download free (1.0.0) Modrinth (pending)Minecraft 26.3, Fabric, macOS on Apple silicon. Install guide. Releases and bug reports on GitHub.
Render scale
Render scale renders the world at a fraction of the window's resolution and upscales it; the menus and the HUD stay sharp. The steps are 50%, 58%, 67%, 75%, 83%, 92% and 100%, the default is 75%, and it applies at once. 75% draws about half the pixels. The upscale is a nine-tap Catmull-Rom filter with a light sharpen. Below 100% the FPS line ends with "NN% scale". The measurement behind the default: at my window size of 1706x1966, in the sunset bay looking down at the water, 75% took the frame from 44.98 ms to 33.95 ms, which is 22 to 29.5 fps. No other single setting comes close. If you need more frames, move this first; 67% is the next step down.
Target FPS
Target FPS is a governor over Render scale. While the median frame time over a settled window misses the target, it lowers the scale one step; when there is room, it raises it again, never above the Render scale you chose. The choices are Off, 20, 30, 45, 60, 90 and 120, and the default is 20, which the tip calls a floor for slower computers that never engages on a fast one. It undoes a step that bought under 4%, so a slow CPU never blurs the picture for nothing; it waits 15 seconds after you enter a world; and after a failed step it backs off for 30 seconds. If you never want the scale moved on its own, set it to Off.
The FPS line, Extended FPS and coordinates
Show FPS puts one line in the corner: the frames per second and the frame time, as a mean over the last 120 frames, followed by "Rockstar Shaders", or by "vanilla" in amber when the pack is not rendering. That amber word is the fastest way to learn that the master switch is off or the pack disabled itself; Troubleshooting takes it from there. Extended FPS adds the last second's minimum and 1% low to the line. Show coordinates adds two lines under it: position and facing, then block, chunk and biome. Overlay corner puts all of them top left or top right. Every overlay hides while vanilla's F3 debug screen is up and when the HUD is hidden. Show FPS and Show pass timings are also on the front page under "General".
Show pass timings
Show pass timings lists every pass the pack runs, in GPU milliseconds, as a running mean with a total row. A pass over 2 ms is amber. Rows fold into "+N more" when the corner cannot hold them. It needs the renderer rebuilt with the GPU timer, which happens when the settings page is closed with Done; until then it reads "passes: timer off". The timer writes a GPU timestamp between passes and reads it back two frames later. For scale, one frame at 1706x1966 in the sunset bay: the water pass 8.7 to 8.9 ms, the terrain G-buffer 3.9, clouds 1.9, volumetrics 1.6, the ray-traced reflection resolve 1.4, caustics 1.4, lighting 1.4 and screen-space reflections 1.4, with the Metal shadow and sky traces outside the timers at 3.8 ms. A screenshot of this overlay is what a performance bug report needs.
Smart leaf culling
Smart leaf culling drops a leaf face when the next three blocks in its direction are all leaves: faces buried deep inside a canopy that nobody sees from outside. Trees look nearly the same and draw far fewer faces. It is on by default, and changing it re-meshes every loaded chunk on the spot, so expect a pause. Measured at a leaf wall, the G-buffer pass was 6.25 ms with it on against 6.66 to 7.14 ms with it off; the cutout layer is half of that pass, which is why leaves are worth culling at all.
MetalFX upscaling and MetalFX scale
These two are present, experimental and off by default. MetalFX upscaling renders the pack below the window size and upscales it with MetalFX, which Apple's documentation describes as upscaling lower-resolution content to save GPU time (read on 2026-09-19). It is a restart-only switch; turning it on also pins MetalFX scale to 67% if no scale is stored, and the scale choices are 50%, 67%, 75% and 100%. Why it stays off: in game the chain dropped from 9.23 ms to between 7.19 and 7.58 ms at 0.667 scale, but detail retention measured 31% on a panning shot against native. Render scale is the supported way to trade pixels for speed.
The rest of the page, and what not to turn off
Zoom key enables the hold-to-zoom on C, on by default and described on Keys and shortcuts. Entities lit by pack draws entities into the G-buffer so they take the pack's lighting; on by default, restart to apply. One thing this page cannot save you: the ray tracing. In the same sunset bay pose, everything on was 27.9 ms; ray-traced shadows off was 29.7, reflections off 29.3, fog off 29.3, and all three off 29.5. Every fallback costs more than the trace it replaces, so leave the switches on Lighting and Shadows and Reflections and Materials alone. The sliders that do save a little are on the quality settings page.
Download free (1.0.0) Modrinth (pending)Minecraft 26.3, Fabric, macOS on Apple silicon. Install guide. Releases and bug reports on GitHub.
Related
Sources
- https://developer.apple.com/documentation/metalfx (read 2026-09-19)
Questions
How do I get more FPS from Rockstar Shaders on a Mac?
Lower Render scale first. 75% is the default and was worth 11 ms a frame at 1706x1966 on my M4 Max; 67% and 58% are the next steps. The quality sliders on the other pages are each worth tenths of a millisecond, and turning the ray tracing off makes the frame slower, not faster.
Why does the FPS overlay say vanilla in amber?
The pack is not rendering. Either the master switch is off or the pack disabled itself after an error. The header on the settings front page says which, and the Troubleshooting page covers both.
Should I turn on MetalFX upscaling?
No, unless you want to see it for yourself. It is off by default because it measured 31% detail retention on a panning shot against native. Render scale is the supported way to render fewer pixels.
What does Target FPS 20 do on a fast Mac?
Nothing. It is a floor that never engages on a fast machine. If you want the governor to work for you, raise it to the frame rate you want, and set it to Off if you never want the render scale moved automatically.
Why does Show pass timings say timer off?
The renderer has to be rebuilt with the GPU timer. Closing the settings page with Done does that, and the overlay fills in after the rebuild.