We can find no bugs with the source code. The reason for the block speed is due to rising difficulty.
Kind Regards,
Raxe.
Actually difficulty has nothing to do with block speed.
If block speed is 1 block in 60 sec then it should be average 1 block / 60 sec regardless of difficulty.
The purpose of difficulty change is to keep 1 block / 60 sec rate.
Difficulty was high yesterday when coin network hashrate was 60+ Mh/s. Today it's dropped to 4 Mh/s because it's just impossible to find a block.