how to stop plug in scanning Logic Pro X

@yoyoBen Thanks and your suggestion got me started but there was a twist. What I discovered was a series of Universal Audio ( UAD ) plugins that were flagged as "Not validated due to internal error" in the Plugin Manager. Catch is I did not want to delete them. I updated the UAD software suite and still had the issue ( rescan at launch ) and warning.

Solution: In the plugin manager

• Select the plugin ( you can select multiple at a time )
• Click on "Reset and Rescan Selection"
• After that the plugin validated. Note it toggles "Use" on by default so you may need to manage.

Solved!!

Short answer: Remove all incomatible plugins from your computer.

Youtube Video: How To Stop Logic Plugins From Rescaning Everytime You Open!

This is also driving me crazy. It used ( a few updates ago) to only scan when there was a version change or new plug-ins were added. Now it is with every launch.