Measurements of magnetic relaxation isotherms were performed as a function of magnetic field and temperature on an exchange-bond-disordered ferromagnetic perovskite Ca <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.2</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.8</sub> RuO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , over an observation time window 10 slestles10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> s, and over a wide range of temperatures which spanned the entire irreversible phase. A plot of Tln(t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> /tau <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) as a function of holding field -H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> was constructed from the times t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> at which the measured relaxation isotherms reversed sign. The plot was interpreted with the aid of numerical simulations based on a model collection of two-level subsystems, which showed that the temperature dependence of the magnetic response of this perovskite was shaped by the coexistence of thermal fluctuations and the explicit evolution of the free energy landscape with temperature, and which yielded estimates for the thermal fluctuation field and for the mean intrinsic dissipation barrier as functions of temperature