IPS is slowing down internet speed and causing Packet-loss on WAN interface

Hello Community,

We have a UTM SG430 and 1GBit/s internet connection.
Now I have noticed that IPS
a. prevents the line from being fully utilized.
b. Long response times (100ms-500ms) and even packet loss occur when the WAN interface is heavily utilized.

With the following IPS exception I was able to calm the situation.
Coming form these source Network WAN-IP
going to these destinations -> Internet

As far as I understand it, this excludes requests from the WAN IP to the Internet. I don't really need an IPS at this point, do I?
Does this exception have any disadvantages from a security point of view?