ViaBTC, one of the largest mining pools in the world, experienced a 50% drop in its hashpower after allocating all of its resources in mining Bitcoin Unlimited blocks.
Bitcoin Unlimited is an alternative project with which miners can decide the size of the blocks they wish to mine. ViaBTC for instance, is mining 2 MB blocks through Bitcoin Unlimited, while the Bitcoin.com mining pool is opting for a 16 MB blocksize.
The team behind ViaBTC decided to move its entire mining pool to Bitcoin Unlimited due to their belief that the current capacity of the Bitcoin network significantly restricts the potential number of people that could be using the digital currency.
As a result, the team has begun to run Bitcoin Unlimited on mainnet, mining its first Bitcoin block on October 10, 2016.
https://cointelegraph.com/news/viabtc-sees-50-drop-in-hashpower-after-supporting-bitcoin-unlimited