This paper studies the performance assessment of linear controllers in univariate feedback control loops, where the processes to be controlled can be approximated by first-order plus dead time models, and the set points are subject to ramp or step changes. The lower bound of the total variation (TV) of control signals is established. Taking the lower bound of TV and that of integrated absolute error (IAE) as benchmarks, an IAE-TV-based performance index is proposed. Four industrial linear control schemes are investigated to find out the conditions simultaneously achieving satisfactory performances in terms of input load disturbance rejection and set point tracking subject to a constraint on the robustness. A novel performance assessment method is presented to calculate the proposed performance index from measurements. Numerical and experimental examples are provided to validate the performance benchmark and the effectiveness of the proposed performance assessment method.