I've been using FileLocator Lite for several years and find it very efficient. The free version (Lite) does search inside some files such as PDFs and text files, etc. I have also used it to find files for my wife that her PC has put in strange out-of-the-way places. It is as quick as lightning and only runs when you use it. Searches are fully configurable and can be saved for future use. It is from https://www.mythicsoft.com