One ongoing concern for blockchain systems is performance. Public blockchains are global systems, with their system resources shared by all the users in the world simultaneously. With such a large user base, resource constraints are a real concern and have already caused real problems. For instance, a popular game called CryptoKitties was launched on Ethereum and caused the network to become congested. Other applications became nearly unusable, as the load from CryptoKitties overwhelmed the network.
The quick and dirty way of calculating the throughput of a blockchain is as follows:
For Bitcoin, the transaction throughput is about 7tx/second. This is because of the relatively small block and the very long block time. Ethereum has short block times but very tiny blocks and ends up at about 14tx/second. Blockchains such as Stellar, Bitshares, and Waves can reach speeds of over, 1000tx/second.