This seems dependent on locate implementation. On OpenBSD, locate is consistently about 4x faster than grep over a list of files. (tried gnu grep, too.)
The plover link brings up some good points, in later slides, about being able to use regex instead of glob.
I like Julia’s blog a lot. She has a very readable curiosity that leads her into interesting little corners. It’s also nice to read a well-written discovery of stuff about e.g. Unix that I’ve taken for granted for 30 years or whatever.