Followers management

It’s not a problem, just a question or curiority about how you manage your followers (or following).
I have an instance and I have follow(ers|ing), after few years, somes of them shutdown.
About the following, I’m writing a script to check for a period, if an instance is up/down. So I can decide to unfollow the instance.
About the followers, I can do the same method, but maybe the instance is down for only one week, two, more… And it could be not polite to remove the follower.
How do you manage this case ?
Is there an impact on performance for peertube to have arround 100 follow(ers|ing) instances down ?
Thanks for your advice,

Tanalahy, I am looking for instances to follow me and I follow them to make our videos more redundant and robust.
this is my instance and I am open to mutual follow, I will follow anyone which follows me (and does not have porno contents)