"Error: Solve failed - maximum time exceeded (29500 ops, 5036 ms)"

Not much to say other than it times out easily.
Maybe an async call is in order? (Freezes the browser tab as well during processing)

[dmarcuse]

The timeout is a safety measure. Due to the nature of the problem, the solver (especially on 4x4 and 5x5) can end up taking an extremely long time, which is why it stops after 5 seconds.

I'll have to look into async a bit more, I'm not familiar with browser concurrency features.

[dmarcuse]

I've improved the heuristic - it's more efficient when searching for a solution now, and doesn't choke as easily. It doesn't fix the freezing, but it helps prevent it from timing out as easily.

Can still manage to time it out on 4x4 / 5x5 with shuffling, however it does definitely have a performance boost. 36k ops now. 👍