As its popularity has grown, so too have transaction fees and processing times. Scalability has largely been restricted by the limits of the blockchain; the transaction ledger that lives on thousands of servers around the world. One faction, Bitcoin Unlimited, believed the answer lied in increasing the code limit on how much data a block can hold. This would make it faster and cheaper for users, but more expensive to run a server. The competing proposal came from Bitcoin Core. It advocates moving smaller transactions outside the blockchain, leaving Bitcoin as a long-term store of value, rather than an everyday payments network.

The SegWit2x upgrade draws on both ideas. Some data will be moved outside of the main network, while block size will be doubled to 2MB. While the move is set to go live later this year, the news appears to have sparked renewed confidence in Bitcoin. The cryptocurrency jumped to $2,628 in trading on Thursday, adding around $316 over the course of just 24 hours. It's now around 15 percent off its all-time high of $3,019, which it reached in June.