It's already optimized to minimize directory changes, which can be performed extremely slowly by some FTP servers, NAS boxes and combinations thereof. Files are deleted, copied, moved (whatever) as 'encountered' in this pattern / as per your rules. Sorting by size and/or action would defeat that. That is unlikely to change.
Bear in mind that if you have limited space, you can make two profiles, one set only to delete orphans (thus freeing space), and the next one set to copy new/changed files (possibly 'only'). The latter can't be done in size order, though.
Bear in mind that if you have limited space, you can make two profiles, one set only to delete orphans (thus freeing space), and the next one set to copy new/changed files (possibly 'only'). The latter can't be done in size order, though.