I happily just upgraded to PD 10 and, despite the wonderful new features that I am enjoying, the transition length problem continued to take up to a minute each time (an eternity in software times. My workaround was to use the Preferences to change the default time to make the change instantly as I applied the transition between photos.
UNTIL . . . I inadvertently changed the Behavior of the transition in PD 10, which I learned about in the tutorial which displayed its new graphic window. I had left it at "Overlap" default over all the versions as it didn't matter to me. Now, as I evaluated Cross versus Overlap, I noticed with delight that in changing the length of the transition, in accomplished instantaneously when my choice is"Cross."
I wonder if I'm the only one who has observed this solution. I think a number of users have complained about this in the past.
Bill Bill Seifert
HP Pavilion Desktop TP01-2022
8 core
AMD Radeon
Windows 11, 16 GB RAM