SYSTEM
- Mac mini (Mac16,11), Apple M4 Pro
- macOS 26.5.1 (build 25F80)
- Razer Synapse for Mac
AFFECTED DEVICES (all RGB devices in the setup)
- Razer Thunderbolt 5 Dock Chroma
- Razer Cobra Pro
- Razer Mouse Dock Pro
- Razer BlackWidow V4 Low-Profile TKL HyperSpeed (via HyperSpeed dongle)
SUMMARY
Dynamic Chroma effects (Spectrum cycling, multi-device sync, audio-reactive, etc.) are
rendered host-side by a single AppEngine (Electron) process and streamed to the devices
over USB / the HyperSpeed radio link. When macOS Game Mode activates (a game becomes
frontmost & fullscreen), the OS deprioritizes this background process and the effect
refresh rate collapses — lighting becomes visibly laggy/stuttering on all devices,
worst on the wireless keyboard. It recovers instantly when the game loses focus.
STEPS TO REPRODUCE
1. Set any dynamic/animated Chroma effect on the devices.
2. Launch a game that triggers macOS Game Mode (tested: Palworld, League of Legends, The Alters, Dota 2 and others); go fullscreen + focus.
3. Observe the RGB animation on all Razer devices.
EXPECTED
Lighting animation stays smooth while the game runs.
ACTUAL
Animation refresh rate drops sharply; effects visibly lag/stutter while the game is the
foreground fullscreen app, and recover immediately when it loses focus.
EVIDENCE (macOS `powermetrics --samplers tasks`, main "Razer" AppEngine process)
Game in BACKGROUND Game FULLSCREEN/FOREGROUND
| Game in BACKGORUND | Game FULLSCREEN/FOREGROUND | |
|---|---|---|
| CPU time (ms/s): | ~100–140 | ~28–47 (about -70%) |
| Timer deadlines <2 ms: | ~520–596 | ~92–168 (about -78%) |
| Wekeups/s: | ~600 | ~130 |
The drop is immediate on focus change and reproducible in both directions across many
samples. "Timer deadlines met under 2 ms" is a direct proxy for animation smoothness;
its ~78% collapse corresponds to the visible lag.
TRIGGER
macOS Game Mode / RunningBoard QoS demotion of background processes while a game holds
the foreground fullscreen.
WORKAROUNDS (user-side, partial)
- Disable Game Mode for the specific game -> lighting smooth again, but the game loses
Game Mode benefits.
- Raising process priority from userspace (renice / taskpolicy -B) does NOT help — the
throttling is at the QoS / GPU-scheduler level, not BSD nice (verified: no change).
DIAGNOSTIC TOOLING
Process priority / QoS measurements (powermetrics, ioreg, hidutil, systemextensionsctl)
were collected and analyzed with the help of AI assistants: Claude Opus 4.8 and Codex 5.5.