Rough numbers: At 300GH/s and difficulty of 1, I should in theory mine one valid block in 3ps (picoseconds), meanwhile at 6MH/s it would take 166ns (nanoseconds).
However, in a difficulty=1 scenario, the difference of 165997ps should make no difference at all. Network latency to other nodes will probably be in the single to double-digit ms range. For reference: 1ms (which is a really good network latency) are a million ns.
Who decides on those 20 minutes anyway? In Bitcoin, there's no need for exact timestamps. Is this different in testnet?
I checked a few of the
latest testnet blocks, and found times between blocks of:
2418404 >
2418405: 20 minutes and 3 seconds.
2418410 >
2418411: 20 minutes and 5 seconds.
2418407 >
2418408: 20 minutes and 8 seconds.
I checked the last 2 days, and to my surprise only 115 blocks per day get mined. I'm surprised because the total block height is much higher than for Bitcoin. I'm also surprised that several people here have mined several blocks per day at difficulty 1, which means that only a few dozen people can do that per day. I'd expect much more people to be mining testnet.