Document dashboard performance modes

README.md

@@ -125,6 +125,22 @@ A self-contained Jarvis-style HUD with:
 - **Space watch** — CelesTrak satellite tracking: recent launches, ISS, military constellations, Starlink/OneWeb counts
 - **Leverageable ideas** — AI-generated trade ideas (with LLM) or signal-correlated ideas (without)
 
+### Performance Modes
+The `PERF HIGH` / `PERF LOW` button in the top bar only changes rendering behavior - it does **not** remove data sources or reduce sweep coverage.
+
+When you switch to **PERF LOW**, the dashboard:
+- Disables decorative background effects such as the radial/grid overlays and scanlines
+- Removes expensive blur/backdrop-filter effects on panels and overlays
+- Stops non-essential animations like the logo ring blink, conflict rings, and corridor flow effects
+- Disables globe auto-rotation and turns off animated flight-arc dashes
+- Converts the horizontal news ticker and OSINT stream into static, scrollable lists instead of continuously animated marquees
+
+Mobile-specific behavior:
+- On mobile, `PERF LOW` also forces the dashboard into **flat map mode** if you are currently on the globe
+- Future mobile loads will continue to start flat while low-perf mode is enabled
+
+The preference is saved in browser local storage, so the UI will remember your last setting.
+
 ### Auto-Refresh
 The server runs a sweep cycle every 15 minutes (configurable). Each cycle:
 1. Queries all 27 sources in parallel (~30s)