Upon activating PoC v4 at 1:50 PM PST on December 2nd we soon realized that the calc_edge_prob had become a performance bottleneck. In response, we changed the order of operations and switched from using sets to lists so the calculation is less costly.

The changes are encapsulated in blockchain-core#303.

The beta deploy was done around 5:10 PM PST and will be deployed to GA shortly.