Try approaching this the same way that you would prepare an ECM:

http://orgmode.org/worg/org-faq.html

Start Emacs with a stable version of Org-Mode, without any additional configuration. 

Is the performance what you expect?

FWIW: two things that sped up my rather small in comparison Org-Mode files were:
- Switching from linum to nlinum
- #+STARTUP: showeverything


Sincerely,

Grant Rettke

On Sun, Jul 10, 2016 at 9:37 AM, Sharon Kimble <boudiccas@skimble.plus.com> wrote:

I'm working on an org-mode file about cancer which is 945.1kb, is
converted to a tex file of 1.0mb and a pdf of 2.0mb with 505 pages. The
conversion is done through this code snippet '(global-set-key (kbd
"s-#") 'org-latex-export-to-latex)'. There is no problem with the
conversion to tex or conversion to pdf.

However, the org-mode file is increasingly slowing down and becoming
difficult to move about within the file, and also enter new information
within it.

How then can I speed it up within the org file please?

Thanks
Sharon.
--
A taste of linux = http://www.sharons.org.uk
TGmeds = http://www.tgmeds.org.uk
Debian 8.4, fluxbox 1.3.7, emacs 25.0.95