Like said in comments, it's mainly important on webserver : https connexion implies for each visitor multiples connexions at each page and so the encryption became a non negligeable part of the ressources cost of the server.

Since in this case server receive a lot less data than it send, and the client ressource consumption is less critical, the server could handle more visitors while using the algorythm A than the B while not changing it's users comfort.

Like said in comments, it's mainly important on webservers: https connection implies that each visitor creates multiples connections for each page and doing so the encryption became a non negligible part of the resources used on the server.

Since in this case server receive a lot less data than it send, and the client resource consumption is less critical, the server could handle more visitors while using the algorithm A than the B, at the same time not changing its users comfort.