I don't really see a reason to implement this. Deathrun isn't really known for its realism and apart from that I can only really see negatives with adding this. Not only could it cause performance problems, but it doesn't seem like many people would want to use it, meaning it would have to be made optional and set to "off" by default like you mentioned. It just seems like extra work for something not many people would use, especially if it causes performance issues for people using it. If more people want it I could look into it but judging from the responses here and the few people I talked to about it, it doesn't seem like many want it right now

Thank you for your suggestion! Feel free to make more if you want anything added.