Not sure about other mods but in case of Traffic it's just a keybind conflict nothing more than that since vanilla added a ton of shorcuts for in-game panels and tools.
If you want to continue using the old shortcut, you can simply remove vanilla one. I don't rememeber which it was but names of conflicting keybinds are displayed when you hover the red "!"
If you experience heavy fps issues, most likely some mod requires an update. You can check the game Player.log, the affected mod is usually mentioned in the spam of errors. Without looking into the game log no one will tell you what is wrong - they will be guessing which will only waste your time on testing if they're right with their guesses or not