[eref]

> simulate a physical environment very fast

That's probably only a problem if it is must faster than everbody else.

> let alone faster than what happens in our environment

That is often not very hard. When a bottle rolls off the table, you can catch it by approximately predicting it's trajectory without computing the precise evolution of the ~10^26 atoms that make up the water bottle. Compression is a corner stone of intelligence. The second corner stone is using compression to choose actions that maximize expected cumulative future reward.