HEIC files open on Mac Photos??

I've found that the HEIC files of photos taken with iPhone open almost as fast as JPG files in Mac Photos, in practice instantly. However, HEIC files created by Fujifilm X-T50 open slowly, in some 6-7 sec. What is strange, the Fujifilm HEIC files are also instantly fully rendered if they are looked using quick look at the Finder level. So, the same files opened in Mac Photos or in Finder show a big time difference in opening. Why is there this difference? Can anything be done to get Mac Photos to open HEIC files fast created with the Fujifilm camera? The slow opening of HEIC files from Fujifilm (compared to those from iPhone) makes the use of this file format unpractical in Photos. MBP M2Pro 32GB MacOS 15.3.2. All comments welcome!