VPN server speed of router ?

It's not depend on router's CPU spec?

Here is some test result of D-link routers (not my own) and my AC68A

PPTP server without MPPE encryption


My ISP speed test

http://www.speedtest.net/my-result/5551524451

Asus RT-AC68A (BCM4709@1Ghz-2cores)

http://www.speedtest.net/my-result/5551536786


His ISP speed test

http://www.speedtest.net/my-result/5447050793

D-link DIR 850L (RTL8197D@600Mhz-1core)

http://www.speedtest.net/my-result/5447062893...

VPN server speed of router ?