Sophos SG firewall deadly slowwwwwww

Question

I just did a virtual machine ESXi install from the VI-SFOS_17.0.0_GA.VMW-80 virtual image that sophos has on their website using the default values (1 cpu, 2 GB RAM, SSD disk). I configured all protection on as part of install. I ran a speediest, and: 
 - my download speed went down from up to 350Mbps using pfsense and squid to 30Mbps running on the same virtual server. 
 I then increased CPU to 4 (on a xeon 3ghz machine) and memory to 4 GB. 
 My speed went up to: 
 - 75Mbps, and CPU utilization based on the control center maxed out at 11%. 
 - I disabled ALL scans, and my speed was 280/350 max. 
 So, I redid an install from scratch on another VM with 4 CPUs and 4GB. Same performance as from imageVM. 
 I then installed to a dedicated fanless i5 router box (4 core, 4GB, 30 GBSSD)- another machine. Without scans, I was able to get my full speed (350/350). With scans, I only get 40/350. Again, CPU utilization is around the 10% mark. 
 Questions: 
 1. Why doesn't the CPU max out? 
 2. Does 32bits limit performance? 
 3. Why on a VM it doesn't hit 350 when all security is off 
 4. why it can only deliver 40/350Mbps with all protection on and why it doesn't use full potential of CPU 
 image of cpu usage spike at turn on https://imgur.com/MhGeO1R 
 config https://imgur.com/RShtcU1

SaschaParis · Answer

Which VM template did you import ? There are various .ovf files, and I experienced, that the ovf8 (VM Hardware Versoin 8) works best. 
 The normal .ovf does not work well from my experience. 
 Also don't expect full >300MBit with a single core VM if IPS and other filters are active. There at least a dual core is required. 
 /Sascha