I found that Search Indexing caused serious ongoing performance issues, so I turned it off. (Caveat: My computer is about 3 years old by now, so maybe this has been fixed in one of the more-recent Win10 updates.)The Windows search function is actually pretty great and fast (I used it all the time for CK2 and CK3), but you have to manually add the folders to be indexed. In Windows 10 you do this through "Indexing Options"* (you can just type it into the start menu) and add the folders from there. Once Windows has indexed them you'll be good to go. Makes life a lot easier when you search for things in the game files a lot (which I tend to do).
Just be careful not to add too many irrelevant folders, or you may end up with a lot of irrelevant results when you search.
*I don't know how to do it in other Windows versions.
Still, even without indexing, the default windows search works perfectly well for me about 90% of the time. I only fall back to Notepad++ in the other 10% of cases where it fails.