Thank you for your reply. I did several tests this week and I have more understanding about what is going on.
My new laptop - 64-bit Windows 11, RAM 32 GB, 32-bit Adobe Acrobat Pro DC continuous release version 2021.005.20058
My old laptop - that I still have and use - 64-bit Windows Pro 10, RAM 64 GB, Acrobat Pro64-bit, continuous release Version 2023.001.20174 installed a year ago,
before I was using Adobe Acrobat 10 and never had problems with optimized PDFs, also users of newer AA could open without problems.
For years I’ve been using the same process of PDF creation, export PDF from ArcGIS at 650 DPI resolution and optimize in Adobe Acrobat with following settings, reduced color image to 450 DPI, Average Downsampling, JEPEG-medium compression. It worked in AA10 without problems. A year ago when I was upgraded to 64-bit AA Pro DC, people with 32-bit AA Pro DC couldn’t open optimized PDFs.
A month ago I got a new laptop with 32-bit AA on 64-bit Windows.
This week I did tests with three PDFs exported from ArcGIS from different projects of different sizes
My new laptop
1) 163 MB of 650 resolution
2) 91 MB of 650 resolution
3) 43 MB of 650 resolution
The huge ArcGIS-exported PDfs opened and zoomed with no problems on my new laptop
I optimized them to 350 DPI for color image and the sizes got a lot smaller
1) 37 MB
2) 15 MB
3) 7 MB
and I opened and zoomed them on my new laptop with no problems.
When I optimized them to 400 DPI, the sizes were
They either opened but I couldn’t zoom in and got a message “There was an error while reading a stream” or they didn’t open and I got a message “Out of memory”.
Every map optimized with setting greater than 350 got this problem.
My old laptop
Everything optimized at 400 DPI (bigger maps), 450DPI (smaller maps) or lower opened and zoomed in without problems.
My conclusion is that 35-bit AA DC cannot opened bigger files although it can process them. 32-bit apps use less avilable RAM than 64-bit ones.
I found on Adoobe website this info
Starting January 2023, Adobe Acrobat and Acrobat Reader will no longer support 32-bit operating systems, including product and security updates. Adobe strongly recommends that you keep your security updates current.
What do you think?
Thank you!
basia