Instead of traditional writing conferences, how about integrating a little technology? Recording your verbal feedback cuts back on manually written comments, allows you to offer verbal encouragement and clarity as you coach their writing, and as a bonus, offers additional listening comprehension practice for students. Use a Voice Memo app (on your iPhone or Android) or an audio editing program like Audacity. Then email or upload the sound file to a shared Dropbox folder for the student to listen to as many times as they want. Realistically, this shouldn't take any longer to note, record and email comments than it does to schedule individual writing conferences with students. In fact, I think it would even save time.
Watch this 2:00 video and let me know what you think. Would this work with your ESL students?