Memory-map files instead of loading them into RAM

When I try to open a very large file, > 10G in my case, the GHex window doesn't appear and in the system monitor I can see that it takes a lot of RAM (way more than 1G; I kill the app before it gets too large). Opening the same file i.e. in wxHexEditor works without problems, window opens immediately and the program takes only ~50M of RAM. Does GHex try to load the entire file into RAM?