heif decoding performance expectations

I have Sony A7CR camera that generates 60MP images (tiled 3x3). However displaying them takes several seconds. Given that I also have RTX 4070 and Core X7 CPU (both having heic decoders), what should I expect in terms of max possible performance? In ideal conditions, what's the performance cap? So far I tweaked libheif to use ffmpeg with heic_qsv decoder and that gets decoding (getting pixels from libheif) to about 2s. I know nothing about hardware, so before I go down the rabbit hole looking at what libheif and ffmpeg do, I'd use some napkin calculation how fast could it possibly be. Human perceive things as instant up to 100ms. heif-info output for image example: MIME type: image/heic main brand: heix compatible brands: mif1, heix, miaf, MiHA, jpeg, SHIF image: 6336x9504 (id=10), primary tiles: 3x3, tile size: 2112x3200 colorspace: YCbCr, 4:2:2 bit depth: 10 thumbnail: 1080x1616 thumbnail: 212x320 thumbnail: 160x120 color profile: nclx alpha channel: no depth channel: no metadata: Exif: 94208 bytes XMP: 57344 bytes transformations: angle (ccw): 90 region annotations: none text items: none properties: none MIME items: 15 : application/rdf+xml