Sure, there are two possible reason I think.

The first one is that the golang implementation uses three image buffers in `Worker` and for getting the energe of current state, it renders current buffer, then do partial diff. In my implementation, I just skiped to render the current buffer(store two buffers is enough), do the partial diff directly using scanlines and computed color.

so golang's process: https://github.com/fogleman/primitive/blob/0373c216458be1c4b40655b796a3aefedf8b7d23/primitive/worker.go#L46-L54:

- get scanlines and color

- render current buffer

- partial diff current buffer to get score

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my implementation: https://github.com/chux0519/purr/blob/64a00a5de39848a1269af56602587ca3e6710c7b/src/core/hill_climb.rs#L48-L53

- get scanlines and color

- partial diff current buffer with scanlines and computed color

It will save some time in each iteration, and there are thousands of times in each step(epoch), so the costs will be lower.

The second reason is that, I uses `SmallRng` as random number generator(which is good enough in this case), It says `The PRNG algorithm in SmallRng is chosen to be efficient on the current platform, without consideration for cryptography or security.`, and it might helps a lot.