Ideal thumbnail size when uploading thumbnail

Hi, I’m uploading a thumbnail both using upload_thumbnail and upload to sg_uploaded_movie_image so that the thumbnail is playable in the overlay media player.
I have a good resolution on the sg_uploaded_movie_image, but resizing on the upload_thumbnail seems to take a long time, so I was wondering if there was an ideal size so that this operation happens quickly, or even providing a size that avoids SG to have to resize altogether.


it’d be lovely to get a reply on this. Thanks