Using 128 GB Lunar SD XD V60 II card on 14 MacBook Pro. Finder is hanging and very slow access to the card data.

Hi ArjaanMahe,

Thanks for posting in Apple Support Communities! Running First aid on your disk can resolve many issues and may fix this performance behavior. Here's how:

1. "In the Disk Utility app  on your Mac, choose View > Show All Devices.

If Disk Utility isn’t open, click the Launchpad icon  in the Dock, type Disk Utility in the Search field, then click the Disk Utility icon 

Note: If you’re checking your startup disk or startup volume, restart your computer in macOS Recovery. See the Apple Support article About macOS Recovery on Intel-based Mac computers. Next, select Disk Utility in the macOS Recovery window, then click Continue. If you check your startup volume (Macintosh HD), make sure you also check your data volume (Macintosh HD - Data).

2. In the sidebar, select a volume, then click the First Aid button

3. In the First Aid dialog, click Run, then follow the onscreen instructions.

4. When the First Aid process is complete, click Done.

5. Repeat steps 2 through 4 for each volume on the storage device.

6. In the sidebar, select a container, then click the First Aid button 

7. In the First Aid dialog, click Run, then follow the onscreen instructions.

8. When the First Aid process is complete, click Done.

9. Repeat steps 6 through 8 for each container on the storage device.

10. In the sidebar, select the storage device, then click the First Aid button 

11. In the First Aid dialog, click Run, then follow the onscreen instructions.

12. When the First Aid process is complete, click Done."

Find these steps in the article Repair a storage device in Disk Utility on Mac.

Hope that helps!