There is a major problem in the blockchain space known as the blockchain trilemma which states that you can only have two out of three main characteristics - security, scalability, and decentralization. Bitcoin has chosen security and decentralization, sacrificing scalability. This results in slow transaction speeds due to the decentralized nature of the network. Other cryptocurrencies like Ripple, EOS, and NEO have faster transaction speeds but sacrifice some decentralization. There is debate around the level of decentralization in projects like XRP and EOS. For example, EOS has fast transactions but only 21 nodes have full power over the chain, making it more centralized than traditional databases.