Encryptions typically compress the data as their first step. It is not needed, but it is the common practice on various, mainly security reasons: in short, the compressed byte stream will be practically redundancy-free, like a random bytestream, which significantly reduces the possibilities of various cryptological attacks.
If you have a slow network connection to your aws VM, then the performance improvement due to the lesser data flow can be higher as the loss due to the CPU need of the compression (+ encryption). It depends also on the applied compression.
In other configurations (slow CPU + fast network) the transfer of the encrypted bytestream might be longer.
If it annoys you, check the CPU usage on the VM. You may play with the MySQL encryption/compression parameters on both of the server and the client side.