"Performance. On Windows I really like to use Everything Search Engine. It provides instant results as you type for all your files and lots of useful features (regex, filters, bookmarks, ...). On Linux I couldn't find anything that's even remotely as fast and powerful."
"Recoll finds documents based on their contents as well as their file names."
"Recoll will index an MS-Word document stored as an attachment to an e-mail message inside a Thunderbird folder archived in a Zip file (and more… ). It will also help you search for it with a friendly and powerful interface, and let you open a copy of a PDF at the right page with two clicks. There is little that will remain hidden on your disk."
Recoll serves a different purpose as it's primarily build to index and search within your personal documents. That's why it doesn't work well when you point it to the root folder, in an attempt to search within the entire system of millions of files and that's also the reason why it's not as fast, since it's doing more work (parsing complex file formats, searching within a more complex database structure and more data, ...).
FSearch is primarily built to find files on the entire system instantly (by that I mean that all results should be ready by the time you press the next character while typing), based on their name, size, time, filetype, etc. This is less work than what Recoll does and that's why it is much faster.
https://www.lesbonscomptes.com/recoll/pages/index-recoll.htm...
"Recoll finds documents based on their contents as well as their file names."
"Recoll will index an MS-Word document stored as an attachment to an e-mail message inside a Thunderbird folder archived in a Zip file (and more… ). It will also help you search for it with a friendly and powerful interface, and let you open a copy of a PDF at the right page with two clicks. There is little that will remain hidden on your disk."