VPN Speeds slower on Router

[wizin]

If I use VPN directly on PC = 98% speed of ISP but almost speed when configured in AC-N66U with 374.40
Is there a workaround, limitation or advice what I should get to have the same speed? on router

 

[RMerlin]

If I use VPN directly on PC = 98% speed of ISP but almost speed when configured in AC-N66U with 374.40
Is there a workaround, limitation or advice what I should get to have the same speed? on router

Your PC has a 3 GHz x86 CPU. The router has a 600 MHz MIPS CPU. It's simply a matter of CPU power.