I second what Rhonda and others have said--bring that seam in about 1/4" so you are not sewing the seam allowances in the mix--should reduce the layers some. And on the pleated style I've found that if I don't overlap the pleats it sews so much better. I had to make 8 dozen "medical weight"--meaning 4 layers of fabric-and it was really rough on my machine--which is getting "spa" treatment but it takes so long these days!
Friend just posted a mask pattern from YouTube (not sure of name)that has the pleats in the front so that it stands off the mouth (not as hot and safer, too). It also looks like much less bulk at the edges too. Think I will try that for next round for family.