Resources needed for traffic shaping

[Slugger]

Just got my opnsense box setup and the basics running.  Ready to add traffic shaping.  My internet connection is 300/100 fibre over provisioned to 325/120.

Before adding any pipes or queues, I do speed tests and consistently hit the 325/120, no problems.  So I setup two pipes: download at 315Mbs and upload at 105Mbps.

Setup rules for all the vlans to put traffic in these pipes with no queues configured yet.  Do a speed test and download consistently tops out at 250Mbps.  Upload does 103-104 consistently.  Decrease the download pipe to 150Mbps and speed test again and get the 149-150 no problem.  Same at 190Mbps.

So it's looking like my hardware isn't able to keep up at ~300Mbps using the traffic shaper.  Is the shaper that resource intensive?  I'm running opnsense on a Zotac CI323 box with 4GB RAM.  Not a beast by any stretch, but is it that inadequate to handle traffic shaping or am I just configuring something incorrectly?

https://www.zotac.com/us/product/mini_pcs/zbox-ci323-nano#spec

Help appreciated.

[Slugger]

Been searching around the documentation & forums.  Haven't found any concrete discussions about the CPU requirements for traffic shaping, but I've tried reconfiguring things about as much as a I can and keep running into the 240-250Mbps max anytime I enable pipes and/or queues.  I'm pretty much resigned to the fact that this is a hardware limitation on my end, but would love to hear from others for confirmation.