Interesting. I remember a gripe being the performance of LINQ wasn't great even for a webapp years back. I'm assuming its negligible nowadays or did you notice less frames when the LINQ runs?
For my game it's irrelevant because most linq loops are only triggered by events so there's no loops running on every frame.
For example, lets say you have state machine based AI, and a scripted event triggers tells an enemy starship to change allegiance. The enemy starship then scans a runtime set of enemy factions using LINQ that are within 3 km to identify new targets to attack.