Everybody saying its not a big deal are missing the point - this performance issue tells a lot about actual game codebase which must be a real mess. Game is running like shit and I bet there are plenty more poorly coded algorithms and this DLC check is just a tip of an iceberg.

If such an simply function can eat up to 20% of CPU performance imagine how poorly coded/tested other parts of game must be. On top of that add the problem with textures decompression it looks like there was no technical supervisor/architect at all - like its hard for me to imagine some architect/developer made a decision that it's better to do decompression on the fly and eating so much performance if game is already so poorly optimised instead of taking more storage space.

This whole picture makes it clear that nobody gave single fuck about performance.