hard fork
I know it will change the voting time and curation

With the current blockchain rules, if authors vote for themselves right away, they get their author rewards, plus 100% of the curation rewards from their vote, plus a portion of the curation rewards coming from everyone who votes for the post after them. Any other curator voting at the same time as the author would get 0% of the curation rewards. This gives the author an unfair advantage over other curators, because the author can earn additional curation rewards through self-voting.

From https://steemit.com/steem/@steemitblog/blockchain-update-3-hardfork-20-and-release-19-4-appbase-statsd-and-rocksdb#@lynncoyle1/re-steemitblog-blockchain-update-3-hardfork-20-and-release-19-4-appbase-statsd-and-rocksdb-20180628t035255050z

Hardfork 20 will change this “lock out” period to a “cool down.” During the last 12 hours of a post or comment payout period, upvotes and downvotes will still be allowed, but their strength (for the same amount of voting power) will decrease linearly from 100% to 0% over that 12-hour period. In other words, it will take twice as much voting power to have the same impact on a post’s payout if the vote is done with only six hours left on the payout window instead of twelve. A downvote cast in the last minute would have virtually no impact.

From <https://steemit.com/steem/@steemitblog/blockchain-update-3-hardfork-20-and-release-19-4-appbase-statsd-and-rocksdb#@lynncoyle1/re-steemitblog-blockchain-update-3-hardfork-20-and-release-19-4-appbase-statsd-and-rocksdb-20180628t035255050z