Reference the illegal records.

I realise the larger files will always take a long time to download and can cause problems with your software.

The most notable problem is that your Adobe is likely to 'freeze' if you hit a key or touch the mouse while a file is still opening.

I obtained a 'fix' from Adobe for my software that creates the PDF's that should theoretically allow you to start viewing the file while it is still loading without freezing it.
The only potential issue is that the fix was written for PDF's that will be viewed by Internet Explorer users, and it may or may not work for other browsers.

That said, people with non-IE browsers and hi-speed lines have not had any problems.

What I have done, to allow you and others to test this, is to rebuild 3 of the PDF's with the fix.
They are the very first 3 on the HCE page "NON-ALPHA", "A" & "B".

They are still going to be slow (NON ALPHA will be the fastest) but if they work, and you find "C" for example (which I have not touched) still gives you problems, then I may have found an answer for you.

Of course, as you downloaded the latest Adobe since you last tried to open anything, you may have already solved the problem yourself.