For me, the WASM version was noticeably slower, with an especially noticeable JIT warmup. It might have been because the asm.js version was running at a lower resolution, so it's not a very fair comparison.

Same for me, asm.js version runs smooth and wasm had lags in few spots and strange glitches with bots getting stuck.

If your browser natively supports WASM, there is no JIT and no warmup time.

Ah, I didn't realise there was no JIT. In that case, I'm not sure what caused it, but there was definitely a lower framerate at the start.

HTML5 is not progressing that fast for games, it's really really slow.