Methods and computer program products for evaluating the performance of a gas lift well. The method includes measuring key gas lift well parameter data and concentration of a tracer present in a substance retrieved from the gas lift well which was injected into the annulus formed between a well casing and a production tubing of the gas lift well. The actual travel time of the tracer which corresponds to a time duration required for injected tracer and lift gas to travel from the injection point, down the annulus, through one or more points of entry of the lift gas into the production tubing is then determined based on a deviation in the concentration of the tracer measured by accounting for variations in a fractal obtained by plotting multiple key well parameter data and a concentration of the tracer in a multi-dimensional time dependent plot.