Frame-Time Monitor: Jank & FPS Percentiles

This simulator models the core telemetry loop behind mobile app-performance-monitoring (APM) tools: sample a frame time every render, compare it against the device's frame budget, and roll the last N samples up into FPS, jank rate and p95 frame time. A scrolling 3D bar chart renders the live frame-time stream — bar height and color both track how close each frame came to blowing its budget — with a translucent plane marking the current budget line. Tune the base render cost and jitter to see how workload variance drives jank, or toggle simulated garbage-collector pauses to see the large, infrequent stalls that are the classic cause of a janky scroll on managed-memory mobile runtimes.