High CPU Load and Packet Loss with Sustained Downloads

[briantho2010]

I migrated from pfesnse to opnsense about a year ago and ever since doing so, I've found that when downloading any large (over 1GB) file over BitTorrent or HTTP/S, my OPnsense box will push to 100% CPU usage and the gateway monitor will show packet loss. The packet loss is confirmed by attempting to browse to any web page, where I see most pages fail to load. It's easiest to reproduce with BitTorrent, but I can reliably reproduce the failure mode by running back to back speed tests + a file downloading in the background.

I found the only way to stop the packet loss is to limit my torrent download speeds to ~50% my internet bandwidth or avoid downloading large files.

I through the issue with Suricata so I disabled it completely and the CPU usage dropped to 60%, but the packet loss issues persisted.

I then thought the issue was bufferbloat with my CPE so I configured CodelQ, verified that I got an A rating on a bufferbloat test and found that the download/torrent issue persists.

Google searching has failed me as I have not found anyone with similar issues. Any help with this issue would be greatly appreciated. If there are any specific logs or parts of the config that would help, I'll be happy to post them.


Opnsense Hardware: HP T730 (AMD RX-427BB with 4 cores), 8GB RAM, 256GB SSD
CPE Hardware: Motorola SB6141
Software: OPnsense 21.7.8 (issue has been present with all versions released in the last year)
ISP: 200 Mpbs down / 10 Mbps up   - IPV4 + IPV6
Services running on OPNsense
AdguardHome
WireGuard
Unbound (for local DNS resolution)
ACME Client
Intrusion Detection (disabled for testing of this issue)