We only provide instant confirmations for bitcoins we know that are going to get included in a block long before the nlocktime will expire allowing you to spend them.
Also, does this mean that to verify a transaction can be considered instant, the merchant has to check with your servers and there is no way of verifying this independently? Isn't this a serious privacy problem?
The minimum is 1 day or 144 blocks, default to 90 days, max is max block size.
probably that is the right step toward solving the transaction speed,albeit by a slightly more centralized workaround,it reminds me of a comment I made almost a year from now:
https://news.ycombinator.com/item?id=6130813
great job ;)