FrameMaker 2019 + DITA Performance Issue

Hi everybody, this is my first posting.

I have switched from FM11 to FM2019 hoping that my DITA files would open more quickly. Alas, for files with key or conkey references, the opposite is true. It takes 3 to 4 times longer to open such files with FM2019. Is anybody else having this issue?

My environment:

• Esprimo P400
• Intel Core i5-2310 CPU
• 2.90 GHz
• 16 GB RAM
• SSD hard disk (all DITA files are on that disk, nothing is on network drives)
• Windows 10 (64 Bit)
• FrameMaker V15.0.4.751 (64 bit)
• DITA-FMx plug-in (the file opening times are the same with the built-in DITA 1.2 structapps, but the plug-in enables key references to key definitions with text strings, such as keywords, to be resolved -- among other things).