Strange and slow internet traffic

If you turn off Web Protection, does it speed up?

Little poor description... what means "strange"  and low quality traffic? From where?

Also useful to know would be, how much ram, what NICs (intel or realtek?) used, which sw and version?

You also could try to deactivate IPS under network protection.

If that or web protection causing those problems try to adjust their settings.

I won't turn off web protection.  That's the principle use-case of having the UTM.

When I turn off IPS I get 23% improvement in download and 395% improvement in upload

Turning off both IPS and Application Control, I get +123% download and +391% upload.
It seems my CPU is the primary problem.  Too slow and/or not enough cores.

Well, yes I am aware.  I'm talking about troubleshooting here, not keeping it off. 

There is a reason for this step.

Edit:  Just noticed your CPU.  Therein lies your issue.  It's a mobile platform CPU that won't keep up with your Web/IPS filtering very well.  It does the job, but you won't see the speed you want.

I just purchased a mini-ITX machine with an i7-7700

• # of Cores 4
• # of Threads 8
• Processor Base Frequency 3.60 GHz
• Max Turbo Frequency 4.20 GHz
  
  

This should take care of things

OK, an i7-7700 should be fast enough in the most cases...the question now is: what connection speed do you have from your ISP? Which theoretically and practically?

with that "U" Modells, which are trimmed to save energy , you have usually low clocked / understepped cores...so that would definitelly be the problem here.

Gigabit but with a VPN