The blocks must have been on a soft fork,
"genproclimit" : -1,
"hashespermin" : 8.60285533,
Thats with a 8 core AMD ..so expect blocks to get very slow when the difficulty goes higher.
00:46:07

{
"proof-of-work" : 0.00000000,
"proof-of-stake" : 0.00000000,
"search-interval" : 1
}
00:52:20

getdifficulty
00:52:20

{
"proof-of-work" : 0.00000001,
"proof-of-stake" : 0.00000000,
"search-interval" : 1
}
The PoW is insanely hard , i bet once it reaches 0.00000005 you'll see a drop in block production rate. i'd be shocked if the difficulty ever reaches 0.000001 in this coins entire PoW lifetime.