5-Toolkit GUI Bake-Off (GPUI vs. AppKit vs. Qt 6 vs. egui vs. Slint)

[BarutSRB]

I'm building something in rust for macOS that requires extreme responsiveness and performance, so I had to do my own testing for my use case and here is the outcome. Maybe someone will find this information valuable.

5-Toolkit GUI Bake-Off (GPUI vs. AppKit vs. Qt 6 vs. egui vs. Slint)

Test methodology (Apple M4 Max, 36 GiB RAM, 5K display @ 144 Hz, 100,000 synthetic rows, 600 strict centered scroll steps):

Frame Timing & Latency (15 fresh processes per toolkit)

Candidate	First Frame (Median / p95)	Ready Time (Median)	Scroll p50 / p95	Scroll p99 (Worst)	Max Frame Latency	Slow Frames
AppKit (Native)	155.1 ms / 165.8 ms	194.3 ms	6.95 ms / 7.15 ms	7.87 ms (13.88 ms)	15.15 ms	0
GPUI 0.2.2	152.5 ms / 159.6 ms	219.1 ms	6.95 ms / 7.41 ms	8.29 ms (8.61 ms)	18.89 ms	0
egui + wgpu	158.1 ms / 165.2 ms	233.6 ms	7.03 ms / 11.30 ms	11.68 ms (12.67 ms)	15.35 ms	0
Slint + FemtoVG	190.2 ms / 252.4 ms	295.6 ms	6.95 ms / 7.10 ms	13.82 ms (16.09 ms)	20.37 ms	0
Qt 6 Widgets	201.8 ms / 236.6 ms	282.2 ms	8.36 ms / 10.03 ms	10.93 ms (11.73 ms)	28.00 ms	1–2

Resource Consumption & Binary Footprint

Candidate	Peak Resident Memory (RSS)	User / System CPU	Binary Footprint
Slint + FemtoVG	117.6 MiB	0.94 s / 0.23 s	9.1 MiB
egui + wgpu	121.7 MiB	1.17 s / 0.58 s	9.3 MiB
AppKit (Native)	124.3 MiB	2.07 s / 0.17 s	0.5 MiB (+ system AppKit)
GPUI 0.2.2	125.5 MiB	4.06 s / 0.23 s	3.8 MiB (standalone)
Qt 6 Widgets	214.5 MiB	4.58 s / 1.08 s	0.1 MiB (+ >22 MiB Qt runtime)

Key Marketing Takeaway: GPUI achieved the fastest startup of all candidates (faster even than AppKit's initial window handshake), best cross-platform scroll p99 (8.29 ms), and delivered an ultra-lean 3.8 MB standalone binary with zero shared library dependencies.