Conditional formatting and a formula for the name of the ACTIVE worksheet

[RandomizerTX]

Sorry for the wordy post, but I want to be clear.

Question - Part A: My workbook is slow because (I think) of a lot of conditional formatting (CF). Does CF recalculate on the fly on ALL worksheets? Or equivalently, if I'm working on SheetAAA, and SheetBBB has a ton of CF on it, does the CF on Sheet BBB slow Excel down while I'm working on SheetAAA?

If so, then...

Question - Part B: I want to turn off CF for all but the ACTIVE worksheet. That is to say, while I'm working on SheetAAA, I don't want the CF on SheetBBB to recalculate and slow me down. Can I do this?

Question - Part C: If it's possible to do what I need, then what's the best way?

Background: I have a back-of-house worksheet called Refs. One way to do what I need involves creating a cell on the Refs worksheet (let's name that cell ActiveSheetName) whose value is always the worksheet I have active at the moment. If I move from SheetAAA to SheetCCC, the value of ActiveSheetName should change from "SheetAAA" to "SheetCCC". Then, I can create CF on every worksheet that determines whether the value of ActiveSheetName is the same as the worksheet where the CF is defined. I can then set it to "Stop If True," which will shut down all the later CF rules on that sheet. Capeesh?

My search for a formula to return the name of the active worksheet leads me only to formulas that return the name of the worksheet on which the formula is entered, whether it's the active sheet or not.

BTW, I'm hesitant to use a user-defined function, because they slow Excel way down on their own.

Thanks in advance.