Depends what you call a decent time window. It’s still a challenge today mostly because of sha256 which is horrible to prove and of course we have a prove an insane amount of sha256 hashes. We will likely have at some point to built a sha256 built in to speed things up drastically. Right now the proof is only the block header not the full block, we need to remove the sha256 bottleneck to be able to do this efficiently for the full block.