Oliver in my opinion I would role back to CC2018 should you be on a mission critical project. The Lumetri coloring you did might go off slightly buy it should be a relatively easy fix. Once Adobe looks at the issues and releases a patch update all should stabilize.
Is the main source of your slowdown related to switching stabilization techniques?
Have you checked with Mercalli to see if they have or are working on an updated version of their plug-in for 2019?
Premiere Pro Team
even projects without mercalli are super slow in rendering.
Mercalli and one other third party plugin provider both say their plugins don't work with CC 2019 anymore.
I have no AE links by the way, all is just in Premiere.
One other thing by the way: I had the most weird error when converting projects from 2018 to 2019:
What often happened in the past is that the audio tracks of camera clips didn't work anymore. What happened this time with certain footages is that the clips got out of sync. In the timeline the last segment of the clip was somehow grayed out. Anyone ever seen this? I had to manually fix dozens and dozens of clips.
And then there was a wedding video project which always crashed. The support just closed by support ticket because they had no help.
I am thinking of switching to Resolve and I know I am not the only one.
The slow rendering issue needs to be fixed asap.
This performance issues could be related to driver version. Which GPU do you use? Can you share other machine configuration details? Are you using a laptop with dual GPUs by chance?
For Quadra cards, Nvidia is recommending version 411.81. I would recommend trying that driver.
For some of the issues related to upgrading mid-project including the clip duration / stripes issue, it can often be a good idea to manually delete two media cache folders. This can take some time to regenerate files if you are working on a very large project so please keep this in mind.
Here is a post with great info on resetting media cache.
Please delete your media cache folders and try Quadro driver 411.81. Please let me know if that helps.
If not, we can definitely provide more support and help you get to the bottom of this issue.
I'm using Quadro M4000 411.81 on a Win 10 Pro machine with no issues applying Mercalli V 2.
Premiere CC version is 13.01
I'm still on CC 2018 to finish all my current projects, so I've only done a few little test routines on CC 2019- so far, so good.