Input Latency Mastery

01 // Polling Rate vs. Scan Rate

There is a critical distinction between how often a keyboard *reports* data and how often it *scans* its own matrix.

• Polling Rate: The frequency (in Hz) at which the PC asks the USB controller for updates.
• Internal Scan Rate: The frequency at which the keyboard's MCU checks the physical switch states.

A keyboard can have an 8000Hz Polling Rate, but if its Internal Scan Rate is only 1000Hz, the effective accuracy is still limited to 1ms intervals. True high-performance boards synchronize these two frequencies.

02 // Browser Input Pipeline Jitter

When testing in a browser, your input travel through several layers: Hardware → USB Buffer → OS Kernel → Browser Process → JavaScript Event Loop.

Each layer adds potential **Jitter**. The Cytific KB Tester bypasses standard throttling by utilizing pointerrawupdate and high-resolution performance.now() timestamps to isolate the physical reporting interval from the browser's paint cycle.

03 // The "Debounce Delay" Tax

Physical switches need time to stop vibrating (bouncing) before they are considered "pressed." Traditional debouncing algorithms add a static delay (e.g., 5ms or 10ms) to every press.

Advanced Optimization: Modern "Hall Effect" or optical switches don't suffer from mechanical bounce, allowing for 0ms Debounce. This can shave up to 15ms off your total reaction time in competitive environments.

04 // OS-Level Latency Tuning

The operating system itself can be a bottleneck. To achieve the cleanest results on our diagnostic graphs, consider these professional tweaks: