Resolved by rolling back Filterable Portfolio to 1.4.0 ! (10mn after writing the topic, & I tried a thousand thngs before doing that..)
Thanks for the über-quick answer !
As I said, I tried with everything I could: .jpg, .bmp, .png.
I tested various sizes too. 15+Mb would never end, & ‘regular’ images at ~1Mb took like 5mn to complete.
