Browser	-
OS	-
Version	-
Automatic VSYNC	-

VSYNC Prerequisites:

TestUFO Solo App & Tab: Close all other apps & Close all browser tabs. IMPORTANT! Exit Background Software: Even Task Manager & RGB lighting adds lag & microstutter. Apple Safari 17+: Please turn off setting 'Prefer Page Rendering Updates Near 60fps'. Linux: Please configure Wayland & browser correctly with high-Hz supported graphics driver. Enable GPU acceleration: Please run natively (no VM). Verify chrome://gpu settings. Multi-monitor: Use primary monitor. Disable multi-monitor. Single-monitor is more reliable. Laptops: Use "Performance Mode" & AC power for faster performance. Close other apps/tabs. External Displays: Turn off your internal display & close your laptop lid. Kiosks & 360+ Hz: Use Kiosk mode (&kiosk=1) to fix stuttering from browser memory leaks. Stuck at 60Hz: If you have a high Hz display, please see fixes for TestUFO stuck at 60fps. Stutter Tester: To diagnose stutters, see animation time graph. Submit screenshot if needed. Submit Feedback: Send bugs & suggestions to TestUFO Issue Tracker.

Supported Browsers:

Web Browser	Minimum Version	VSYNC 60 Hz	VSYNC 120 Hz	VSYNC 144+ Hz
Chrome	16+
Firefox	24+
Edge	79+
Opera	15+
Mac Safari	17+		*	*
iPadOS Safari	17+		*
iOS Safari	18+		*

*Safari requires setting "Prefer Page Rendering Updates Near 60fps" to be turned off.

User Agent:

Notice for Developers, Browser Vendors & Standards Groups:

Yes, useragent detection is not recommended. However, whitelisting was necessary for scientific-quality VSYNC.
For web standards groups (W3C / WHATWG) working to standardize VSYNC discovery, please contact us.
For browser vendors who needs help to be whitelisted above 60Hz, please contact us.