Engineering Sub-15ms Input Latency: SendInput, TCP_NODELAY & Zero-Copy Framing

Why do some remote desktop sessions feel sluggish even on a gigabit fiber connection? The culprit is rarely network bandwidth — it is Nagle buffering, user-mode message queue delays, and synchronous frame encoding.

Eliminating Nagle's Algorithm with TCP_NODELAY

Hardware Scancode Injection via Win32 SendInput

Instead of posting synthetic window messages that fail in elevated UAC windows or 3D viewports, SimpleViewer injects hardware scancodes and normalized 16-bit absolute mouse coordinates directly into the kernel input stream.

Backpressure-Aware Frame Pacing

By monitoring socket send-queue depth on port 7891, the host encoder never queues stale frames behind congested packets, keeping mouse and keyboard feedback instantaneous.