At least 5 hours before serving, peel and pit 4 of the peaches. Cut the fruit into 1-inch pieces and freeze immediately, in a single layer on a cookie sheet. Refrigerate the remaining unpeeled peach.

A few minutes before serving, place the frozen fruit pieces in a food processor or blender and pulse about 8 times then process continuously, scraping down the sides of the work bowl, until the fruit is finely chopped. Peel and pit the refrigerated peach and cut into chunks. Add this and the lemon juice and confectioners' sugar to the work bowl and process until the mixture is smooth and creamy, scraping the sides when necessary. Taste for sweetness and add more sugar if necessary. Serve immediately.

Mixture may be frozen at this point. Cut the frozen mixture into 1-inch chunks and process until smooth.