Hello,
Can you confirm that to protect against MITM attacks with CIS it is important to activate the “anti ARP spoofing” function in the firewall settings?
In previous versions this enabling slowed my internet connection, while now it seems that it does not slow it down (until now).
Furthermore, is it also useful to install Internet Security Essential (if it also protects browsing with Chrome)?
Thank you. 
it is important to activate the "anti ARP spoofing" function in the firewall settings?Only you can define what is important enough to use. Some turn it on, some dont.
“anti-arp spoofing” Its mostly for LAN networks , If your running issues with your LAN, I would recommend filling out a bug report or just disabling it to see if it works. Its not a big deal, but nice to have in most cases. You wont lose any sleep if its disabled ARP Poisioning isnt common. There may be a very small chance it’ll interfere with your printer and I’ve only seen that once in my lifetime. Also blocking “ip fragments” setting could be a issue for the printer too but thats a totally different setting
Furthermore, is it also useful to install Internet Security Essential (if it also protects browsing with Chrome)?Again only you can decide if its usefull or not. If you run into issues that affects your machine either disable it or file a bug report so it can work fine on your machine. Some turn it on and others its off.
Regardless of what you do, if you disable both of them. Dont lose any sleep over it. The firewall, autosandbox and/or hips, viruscope will have you covered.
Well said, that’s applicable for every setting.
Ok thanks! 