I'm with Bridwidder. Like you, Wincing Devil, I often use a giant print lyric or lyric/chord sheet the first few times I do a new song in public, precisely because I can sing the song through a dozen times flawlessly in my car or living room and then draw a blank in the middle of the song the first time I perform it in front of a group.
[This is not surprising, since the stimulus situation in which the song was learned is notably different from the one in which the memory will be tested, by virtue of the audience demanding some of your attention in the latter situation and not in the first. If you memorized the song by singing it to, say, your family, you'd be less likely to go blank when singing it before a different audience.]

Using a very large print, I can glance at the sheet PRN, from 4 feet away, without being obvious about it. [And in a song circle, 7 or 8 people can sing along with me from the one sheet!]

NoBiscuit, I have the opposite experience as you, it seems. Knowing I have the lyrics with me makes me more likely not to freeze up and forget them. Usually I find that after I make up one of these lyric sheets I seldom have to actually refer to it, and if I do, it's only for a quick glance at the beginning of the next line.

Rich M, and Mooh, you bring up a good point. Some people do not memorize and retrieve lyrics nearly as readily as others. And, while I can accept "the folk process" for what it is, it saddens me to have someone's exquisite lyrics bowdlerized because singers relying on their imperfect memories fill in the blanks during live performances with whatever words pop into their heads. Especially when you're singing a song that:
• you didn't write
• isn't one that "everybody knows" and
• really would suffer by forgetting a verse or blowing a line,
I would prefer that you use a cheat sheet and sing the lryics correctly.

On the other hand, if the lyrics aren't the highlight of the song, maybe it's better to sing it with feeling and invent new lyrics than to use a lyric sheet.

In our church choir we usually do have our sheet music in front of us when we perform, but our eyes are on the choir director about 97% of the time, just occasionally glancing at the words and/or music. Part of the trick is to have the sheet music in a position such that you can glance at it without lowering your head.

I saw Nanci Griffith perform live last summer and on several songs, she put sheet music [presumably] on a music stand by her mic. I never noticed her "using "it. That's the point: if you're gonna use it, be subtle enough that it doesn't detract from your presentation of the song.

Genie