The new AMD-based instance types are made available in Nov 2018. It’s damn impressive. Here is a quick benchmark using openssl.
The first is from EPYC, second from ARM, third from Intel.
Below is what an AMD Ryzen7 2700 does
▶ openssl speed -engine padlock -evp aes-256-xts type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes 16384 bytes aes-256-xts 448645.64k 1723738.09k 3990048.43k 5924899.84k 6806233.09k 6963849.90k
Yes, AWS also launched ARM-based instances.