Hello, My experience is that there is some correlation between the number of src blocks and/or tables and performance. I haven't done any analysis but I do find that emacs lags when attempting to navigate some of my large org files with many tables and src blocks.
However, I see no performance hits when working in large org files with many headings and levels but little in the way tables or src blocks. You may wish to try changing the values of some of the fontification variables, such as ,----[ C-h v org-src-fontify-natively RET ] | org-src-fontify-natively is a variable defined in `org.el'. | Its value is t | | Documentation: | When non-nil, fontify code in code blocks. | | You can customize this variable. | | This variable was introduced, or its default value was changed, in | version 24.4 of Emacs. `---- if you do have src blocks in your large files. -- : Eric S Fraga (0xFFFCF67D), Emacs 24.4.50.2, Org release_8.2.5h-842-gad16ef.dirty-git