The new version, which calls itself Bitcoin XT, would increase the block size to 8 megabytes, which would allow up to 24 transactions to be processed every second. That is still a fraction of the 20,000 or so that VISA can process, but would increase every year, so that bitcoin could continue to grow.

Those who oppose Bitcoin XT say the bigger block size jeopardizes the vision of a decentralized payments system that bitcoin is built on, as the extra computer memory needed would shut out many of the thousands of individual “nodes” that currently power the network.