I don't think you understand quite how the Steem blockchain works... It runs on a Delegated Proof Of Stake, not Proof Of Work. Its governance model is consensus based which means the top 19 witnesses would have to agree to a fork in order for it to happen and that's why it's important to vote for the right witness. There is no need to speed anything up since Steem's transaction speed is 3 seconds. As for spam, that is why we have the flagging system.