In my case, flowd_aggregate.py or php-cgi was not a culprit, as it showed by the top command. I disabled IPv6, and it dropped CPU utilization from 90-100% to less than 10%.
Please find the following details.
https://www.analysisman.com/2020/10/opnsense-highcpu.html
Hope this helps!
Please find the following details.
https://www.analysisman.com/2020/10/opnsense-highcpu.html
Hope this helps!