Fotos is extremly slow using HEIC from Sony camera

Hello, when using HEIC (HIF) fotos from a Sony camera (Sony alpha 7cr with 61 MP) it takes about 16 sec to see the foto in full screen on my MacBookPro (M2Max 96GB) and about 8 sec on my MacStudio (M2Ultra 192 GB) - even exporting these fotos to JPG is unbelievable slow. I have no problems viewing anything else. I use the newest OS and made all updates...