yes, thanks for the info about new version of gmic! i installed and now it seems it's not working in my case. i have jessie debian, linux. maybe because i have an older version of gimp [2.8.14], i don;t know. the process of previewing .cube it's not working now.
what os you have?
resolution of .cube file, i really don't know. one .cube file has 5 mb.