new File and memory use

I’m working on a logfile system for a project, which might get quite
large — thousands of lines. I’m wondering if anyone knows if the new
File() command actually puts the file into RAM, or if it just makes it
accessible to reading/writing (I would only be writing to it, so I’m
talking about the command: new File(foo, write, TEXT)

Has anyone looked into this/

Thanks,

M