No, notepad++ can't load big files. Exceed simething like 500mb and it will just rollover and die (with a message).
Sublime does so better.
However notepad++ prompts me if I want to reload the logfile in question if it is changed on disk - it will be every second in my case. I can then press "no" in notepad++ to be able to view the file. In sublime it just reloads and reloads and reloads. The one fix is to copy the logfile and then open the copy in sublime text. That is just a crappy workaround.
I would like to be able to disable auto-refresh for large files. Perhaps it should just start to prompt me for them, that would work too (if it remembered my "no").