Acceleration and cooling timescales (measured in the jet frame) expected for high-energy protons for an intermediate luminosity bin, 10⁴⁶ erg s⁻¹ <  L_γ <  10⁴⁷ erg s⁻¹. The blue line shows the photomeson timescale t_pγ. Green lines show an estimate of the acceleration timescale for three values of the acceleration efficiency η_acc. The orange horizontal line is the adiabatic timescale. All quantities are expressed in the emission region reference frame.