Can someone tell me the logic behind interface queue assignment to VPN interfaces?

I know that Simple Queues are assigned every time there is a speed limit on the interface. However I sometimes see Interface Queues and I cannot figure out when they appear and what type they would be.

For example (the following are all server instances):
on Ros 5.13 PPTP created no interface queue, but OpenVPN did a default type
on an identical, but 5.12 Ros created a only-hardware-queue for PPTP
on older 3.x Ros servers I see default interface queues for PPTP and L2TP

The reason I'm asking is that 3.x VPN seems to perform better than 5.x
Can it be because of the interface queues? How can I enforce these queues for 5.x and where can I set their type for all PPTP for example?


Thanks
GL