1)BRIEF TITLE
Importing images into existing files is really slow in Catalina.

2) STEPS TO REPRODUCE THE ISSUE
Here below you can find the video reference with comparison between iMac Capitan where everything works fine and iMac Catilina where everything works bad.

https://drive.google.com/file/d/1J6XnMl4JVT1OaaerVXq9ViYiZeQm7jsb/view?usp=sharing

3) ENVIRONMENT
iMac Late 2015 / Mac book Pro 2016
Mac OS Catalina 10.15.1 / 10.15.2
CPU iMac: 3,3Ghz Intel Core i7
CPU Mac Book Pro: 2,7 GHz Intel Core i7 quad-core
MEMORY: 16GB

Software: ADOBE ACROBAT 2019.021

4) EXPECTED RESULT
We would expect that importing images in existing file is quick and immediate as it happens on previously OS X (see video reference on point 2)

5) OBSERVED RESULT
Importing images into existing file is really slow: importing 6 images takes 25 seconds (see video reference on point 2)

6) NOTES
We have already contacted the Adobe support and they have confirmed that this is a bug, so they've suggested to contact you.