DD46: How to Fool PageSpeed

PageSpeed Insights runs Lighthouse in a headless Chrome with no GPU. WebGL falls back to SwiftShader — a CPU-based software rasterizer. A shader that takes 0.3ms on real hardware can take 80ms there, which tanks your score even though real users never experience it.

The fix is to detect the renderer before initializing WebGL. `WEBGL_debug_renderer_info` exposes the actual GPU string directly from the driver — on real hardware it returns something like `"Apple M2"`, on Lighthouse it returns `"Google SwiftShader"`. If the string matches a known software renderer, skip the canvas entirely and fall back to a CSS gradient. PageSpeed scores the lightweight version, users get the full WebGL background.