Capture-Image significantly slowing down as SD card fills (Panasonic GH5)

[engei]

When using capture-image with my Panasonic GH5, it initially takes about 5 seconds before it's ready to capture another image. However, once the SD card starts filling with images, the processing time increases significantly. After just 150 captures, the processing time is around 20 seconds. After 300 captures, the processing time is up to a full minute per capture.

According to the logs, it looks like it's having to list every file in the SD card directory to find the last capture, before it allows me to capture again. This is incredibly slow. Is there a way around this?

This sounds exactly like the issue with Nikon cameras as well: #307

I've also tried trigger-capture since I could theoretically just put it on a 3-second cooldown, but it says the GH5 doesn't support generic capture. The docs says it should though.

Panasonic GH5
Sony SF-M64T (277MB/s read)
Raw files ~22MB each saved to camera's internal SD card
Raspberry Pi 4
Latest gphoto2 & libgphoto2 versions