PDF printing - flattening pdf very slow to print.

[swordstar]

So I had this lovely group of pdf documents that I combined into one larger one, only 11 pages, that were created from word documents to begin with. 

When I created the original pdf documents from the word document via the 'save as Adobe PDF' option, the pages would get created and take forever to print as they had to 'flatten' everytime it went to print.  I even tried to optimize the PDF within Acrobat Pro DC, and no luck.  It would still go through this flattening process.  Anyways, I found a solution to the problem of the non flattened document honestly never printing. 

The solution is:  in Word, print the document to the Adobe PDF printer option, then save the file as normal.  Once the group of files were recreated this way, the combined file would print without needing to be flattened again. 

[swordstar]

I had actually tried that on the original document and it didn't help the problem of the flattening message.  On other documents that might very well be the fix. 

I went back and tried this again and under the pdf optimizer, clean up tab, there is no option to remove hidden layers content and flatten layers. 

thanks for the note though.