Same problem here
Document, 30 pages, about 75KB:
- docx takes about 12 sec. to save *
- after saving the document in the old doc-format:
doc takes less then1 sec. to save
Partial Solution
Right click on the status bar on the bottom and disable "Spelling and Grammar Check"
After that saving the same docx takes about 2 seconds
* does not block user actions
(It seems that Word 2013 pointlessly does things that are not really required before/while saving a docx, e.g. a (whole?)
"Spelling and Grammar Check" and .... ? one should try other settings, perhaps there is a additional delay when
"Spelling and Grammar Check" finds Errors, etc...)