I’m not sure what you mean by a realtime enviroment?
Do you mean do that stop connections in real time? Then the answer is yes they do.
Of course they work – is there a benefit yes and no. If your ‘realtime environment” is your domain then normally firewall protection will be done at the internet facing point which wont be your desktop and installing a firewall is just creating more work for your IT team and pointless. Now if your ‘realtime environment” is at home or a notebook user plugging into a foreign network then yes good idea for protection. But yes they work as previous post suggests.