difficulty 9 already, that's the reason
What's the reason it is only 9?
I'm trying to get my head around the idea that Quarkcoin launched a few hours ago and is already 57 difficultly.*
Is that an apples to oranges comparison? Surely Quarkcoin can't have 6 times the network strength of Primecoin.
As Primecoin difficulty rises, the supply of coins really gets choked off - at difficultly of 32 . . . that's 999/(32*32)= .975 coins per block.
*Oh, it's gone up to 63 since I wrote those two sentences.
It is very much like comparing apples and oranges. For Primecoin, the integer part of difficulty determines the required probable prime chain length. E.g. if difficulty is 9.07233632, a probable prime chain of length 9 is required. The fractional part is used to determine how many length-9 chains are accepted. It scales logarithmically so that going from 9.8 to 9.9 is a lot harder than going from 9.1 to 9.2. The details for the fractional part are in Sunny King's paper.
The current algorithm also does more work for longer target chain lengths. That's why PPS numbers are also dropping.