How to fix pfsense packet loss on load increase?

Question

pfSense

There is a mini pc pfsense 2.4.4 N3060 @ 1.60GHz RAM 2Gb.
From the provider pfsense receives the Internet with a 600Mbit channel.
The router is used to organize the work of 3-5 clients and several servers with services, and also raised OVPN and SNORT.
With a download speed from the Internet up to 150Mbps, there are no problems.
Already from 200 it starts to lose up to 5% of packets, and from 300 it increases up to 50%. What is critical for servers with which up to 15 clients are constantly working remotely.
In a peak load of 600 Mbps, the processor is only 40% loaded and the memory is 20%. There is also no throttling.
We have to artificially limit the speed of the Internet at around 200Mbps.
Tell me what could be the problem?