...scaling is a solved problem, and has been since mid-2011. Implementations are now coming into public domain, just as the market demand arises.
...
Aha.
https://www.reddit.com/r/Bitcoin/comments/2t7e11/justus_ranviereconomic_fallacies_and_the_block/Justus Ranvier--Economic Fallacies and the Block Size Limit, part 1: Scarcity by xcslerin Bitcoin
[]theymos 6 points 11 days ago*
There's a hard protocol rule called the max block size which limits the number of network-wide transactions to a few transactions per second. The actual number of transactions per second depends on the size of the transactions, which varies. Removing or increasing this limit would require everyone who runs their own Bitcoin wallet to upgrade their wallet software. A change to the Bitcoin network which requires everyone to upgrade is called a hard fork.
Such a small limit on the network's capacity is obviously undesirable, and many people are a bit horrified that the Bitcoin network is limited in this a way when they first learn about it. The naïve response is to just completely remove this limit, which seems at first glance to be an utterly pointless restriction on Bitcoin's scalability. (Some well-informed people also hold this view and have reasonable arguments.) However, many Bitcoin experts believe that completely removing the limit is fairly likely to cause Bitcoin to become highly centralized, or become too weak against mining-based attacks, or be destroyed entirely. But even if Bitcoin can't handle as many transactions as we'd all like, that doesn't mean that Bitcoin is useless: there are several well-explored but not-yet-implemented ideas for using Bitcoin securely, cheaply, and easily without creating "actual" Bitcoin transactions.
I might try writing an easier-to-understand but still fairly complete and accurate summary of the issue, but that'll take several hours, and I don't have time right now. Until then, here's a propaganda video from someone who supports keeping the max block size at its current level for the foreseeable future, which is not what I support. The video also contains some exaggerated/controversial statements. But it's probably still an OK video for getting the basic idea.