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docs/optimizing.md

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+# Optimizing Tutu
+
+Topic Index:
+
+- Time to first byte
+- Time to first draw: [Load size](#load-size)
+- CLS
+- Framerate: [Algorithm](#algorithm)
+
+## Load size
+
+The baseline for the load size is lowest 3G download bandwidth in 2s, typically 1.1Mbps (or ~137 kilobytes/s) * 2s = 274 kilobytes.
+
+In another words there is 274 kilobytes budget for an interaction without further notice. Notice and progress are needed if the interaction needs than that.
+
+The service worker can use 1 chunk of size.
+
+## Algorithm
+
+Don't choose algorithm solely on the time complexity. GUI app needs smooth, not fast. The priority:
+
+- On the main thread: batching. Batching is usually required to spread the work to multiple frames.
+  - Think in Map-Reduce framework if you don't have any idea.
+- On the worker thread: balance the speed and the memory usage.
+  - Arrays are usually faster and use less memory.
+  - Worker is always available on our target platforms, but workers introduce latency in the starting and the communication.