First - If running multiple instances of Adobe DC, there is NO reason why one instance should cause the other to hang, it's the 20th century and multi-threading isn't new technology anymore, get with the program.
64bit support on Windows 10 would be a big plus.
It takes an average 20-30 seconds to open a SINGLE PAGE PDF. NONE and I mean NONE of the suggestions about turning off enhanced security and what not are helping to make it quicker. Opening PDF files should be near nano second operations, especially single page documents. Since the release of the DC version, performance has been steadily and predictably declining with every new updated.
Auto update text boxes too while you're at it.