Notepad++ doesn't support huge files, according to this wiki documentation, the problem persists if the component (Scintilla) remains as the core of Notepad++ :
Older versions of Notepad++ may crash
while opening very large files. Newer
versions (5.2+) will deny opening the
file and issue an error message. Why
Notepad++ is based on a component
(Scintilla) which is geared towards
providing rich text viewing, with
syntax highlighting and code folding,
as opposed to bulk text services.
There are necessary trade offs.
Loading a 200MB file will require
around 800MB of memory, and the OS may
balk at the memory allocation request.
There are basically two ways out:
- Split the huge file into manageable chunks, and keep only one of them in editor;
- Use another tool which is tailored to handle massive text files.
If you still manage to open a large
file, performance may not be optimal.
Here is a couple things to think
- Plugins which analyse and scan text will slow down NP++, disable them if possible
- Parsing for clickable links on loading the document is slow if the document is large; disabling the clickable links has been reported to significantly help.
Another page on sourceforge also suggests that this problem persists throughout Notepad++'s life, as the community requested to solve this problem:
Why don't you try other software such as gVim? Is there any reason?