Footage looks great in FCPX but jittery after export?

Good Afternoon Everyone and Happy Holidays!

I am running into some issues with Exported footage in FCPX. I import all footage and use the option "leave files in place." I also select Proxy, ProRes, 50% and use this for the majority of my editing. At the end of my edit, I change it to "Original/Optimized" and render the whole file. I then export in 5K at the same resolution and frame rate as the footage. I export in both H264 and ProRes 422. 

In the viewer with "optimized/original" selected, my footage generally looks beautiful. But after export, I find there are jitters in the video. These jitters seem to be there one moment and then I watch the same spot again and they have disappeared and are jittering in another part of the video. At first, I thought it was my drone footage as the RAW footage from the camera does this straight off the SD. But when the footage is in FCPX, it runs smoothly. Any thoughts? I notice this jittering also carries over to YouTube sometimes. 

I don't create optimized media due to file sizes, so it is odd to me that the "Optimized/Original" would run perfectly smoothly in FCPX, but when I export that footage and play it in Quicktime it is jittery. 

My machine is a Macbook Pro 2020 and has 32GB RAM. The machine uses an Intel I7 2.3 ghz

Thanks for your support and any guidance you have!

Laptops are not the most powerful machines in general. I'd not be surprised it has trouble playing back 5K video. That's all you're seeing, the laptop struggling to play the video, due to it being 5K.

In FCP, you're playing much smaller, lower resolution proxies, so yes, it plays back just fine.

I'd love to download the clip you exported to test on a couple of different MBP laptops here, for comparison, and on my iMac Pro.
benb at bbalser dot com

JoeEditor wrote:

Laptops are not the most powerful machines in general. I'd not be surprised it has trouble playing back 5K video. That's all you're seeing, the laptop struggling to play the video, due to it being 5K.

In FCP, you're playing much smaller, lower-resolution proxies, so yes, it plays back just fine.

I'd love to download the clip you exported to test on a couple of different MBP laptops here, for comparison, and on my iMac Pro.
benb at bbalser dot com

Thank you, Ben. I could understand this if I were using proxy only in FCP X, but when I switch back to "Optimized/Original" and go full screen, it still plays smoothly for the most part. I don't optimize my media, so assume when I click over to "Optimize/Original" it is showing me the original media? 

As soon as I play that media outside of FCPX post export (or pre-import), it jitters. This happens in 4K also. I was unable to upload the files for you because I have a basic Dropbox account, and it won't allow me to post larger files, but I found another file that has noticeable jitter straight off the SD Card that improves in FCPX and then is back again after export. I have attached it in the link below:

www.dropbox.com/s/j0gdrr8x4400uqz/DJI_0008.mov?dl=0

This was a 4K slow drone pan, and on my laptop, there is fairly significant jittering happening. If this plays smoothly for you, I know it must be my laptop! Thanks so much for your help!

It plays smoothly for me on a 2019 16" MBP in the QuickTime player. 

Thank you, Tom! Guess it is my machine then.