The purpose of this kicking function that the original poster wanted to have it there for, would end up completely ineffective and the changes it would do to reduce the lag wouldn't be noticeable by anyone if the time period would be as much as 2 hours, even straining down on one hour it still wouldn't make much difference, players would easily be able to just go on and move their mouse if they wanted to stay in game, a system like this will not prevent anyone from not sitting still and doing "nothing", even if you are sitting still in the game you are taking part, even if you tab out and check other things you are also still taking part, being kicked for the reason of causing lag for others is ridiculous. If I'm going to be honest it's not going to make much of a difference even if it was set to something like 10-15 minutes idle and then kick, the only thing it would bring would be annoyance upon many of the regular players of the game.
I can understand the logic and reasoning for kicking users after a few hours of inactive to protect them and their character. I can also understand some logic if it would be for the sake of getting more player slots, lets say a full server and people trying to get on constantly but being unable to do so since there's lots of players just idling and not actually playing the game.
But not to reduce client sided lag caused by slower systems.. That's taking things too far, this might sound quite rude to some extent and I understand not everyone has the same access to as good computers as some might have, but to my understanding so much was held back on this game to just make it run decently on older hardware and computers, in this case what you can do as a user if you get lag to such an extent you cannot even play, cannot even move, cannot even connect, is to look for optimizations, running the game in lower quality or even check for a new computer anytime soon, sadly this game might not run well on a lower end computer back from 2004 or an older desktop filled with bloatware slowing it down. We should not forget that others might not have it as well and smooth on their systems, but kicking players left and right after a few minutes idle because they "might" be sitting in a spot that "might" cause lag to "some" users I really cannot grasp.
The way this game is running and optimized could and will lag many computers out there, and what has been proven to cause the biggest amount of lag and frame drops for players is nothing else but other players characters, the lag will be there, more or less for some depending on what they are running the game on, and what sort of quality settings it's using.
Just as ruby mentioned above I myself would probably end up not going on FeralHeart all together in the end if I knew I'd get kicked every 5 minutes, some of us need to check in on other things, and even if we'd set this timer to something higher like 30 minutes, 1 hour, 2 hours, it wouldn't have any effect on the lag or the reduction of it. Kicking players for less lag is just a system that couldn't work well.