RDRAND has a throughput of hundreds of megabytes per second on most processors. Getting 226 bits is pretty easy, even shuffling millions of decks per second you

RDRAND has a throughput of hundreds of megabytes per second on most processors. Getting 226 bits is pretty easy, even shuffling millions of decks per second you'd be bottlenecked elsewhere. (That does sound like a fun optimization challenge: "write a program to fairly shuffle the most decks of cards per second possible.")