IPS slows down internet connection (Fiber Gigabit)

There are quite a few threads about this.  The measurement you're seeing is about the best one can get when working through Snort as it is single-threaded.  If you have a quad-core CPU, you will be able to fill a gigabit pipe with four simultaneous tests from four different devices.  If you identify specific sites that you can trust, you can make an IPS Exception for them.

Cheers - Bob

Thank you so much for your replies. I would hate to create rules for individual sites, that would be like a never-ending process.

So if i understand this correctly, in order for me to use IPS feature in UTM, i might need to upgrade my CPU to Quad Core, until then i should keep it disabled?

I will start hunting for a cheap quad core CPU, and motherboard. What is the ideal size of RAM you would recommend for this endeavor?

I am sorry, i totally forgot to post my current hardware specs.

I am on a 8GB memory, with i3-2120 3.30Ghz CPU.

I think its dual core, So now we are at the most important question. What would be an ideal CPU that can handle 1-2gbps internet bandwith? I do get a burst of 1.5 to 1.7gbps every once in a while.

For IPS (snort) the clockspeed of the CPU is the most important; the higher the clockspeed, the higher the throughput. Like Balfson told before, snort only uses a single core for a single connection, so if you're doing a speedtest from one device, this device will only get 1 CPU core. However, the other cores are still available to other users/devices. 

To get the best possible IPS speed using just 1 device, you have to use a clockspeed as high as you can find/afford. More cores will only help more simultaneous users and can be beneficial in a larger network.