Bridge 15.0 Photo Downloader performance

My workflow uses Bridge to copy images to an external SSD, from which I select the photos I want to import into LrC. I am running macOS Sequoia on an M3 MacBook with lots of ram. All has worked well until, suddenly, the whole process has slowed to a crawl. The photo downloader takes an age to load/render the thumbnails so that on a big CFExpress A card it can take many minutes just to get through that first stage. Once selected, the photos are also taking much longer to copy over.

I have tried different cards and readers but the result is the same. I have uninstalled/reinstalled Bridge.

What is confusing to me is that it was working fine after the Bridge 2025 update and I don't think there have been any other updates since. 

anyone else sharing this experience?