Labour would not make appraisal compulsory and would not link staff development and appraisal to pay, Helen Liddell, the party's Scottish education spokeswoman, told the conference.
"I have been a personnel director and I know that one way not to make it work is to enforce it," Mrs Liddell said. But she warned that teachers should not take Labour for "patsies".
Mrs Liddell was responding to Dick Lynas, head of Taylor High, Motherwell, who said that North Lanarkshire's agreement on performance review with the teacher unions was already subject to "rumblings of concern" because of the limited resources available.
Heads also told Mrs Liddell any Government should press on with Higher Still. Ben Conway, head of Columba High, Dunfermline, said: "We are desperate to do something for a large number of pupils who are shortchanged. We are very fearful Higher Still will be put back too much."
Mrs Liddell said her commitment to delay the reforms was based on soundings from the teaching profession which was already complaining of "change overload".