A first-principles investigation of cubic BaRuO$_3$ , by combining density functional theory with dynamical mean-field theory and a hybridization expansion continuous time quantum Monte Carlo solver, has been carried out. Nonmagnetic calculations with appropriately chosen on-site Coulomb repulsion $U$ and Hund’s exchange $J$ for single-particle dynamics and static susceptibility show that cubic BaRuO$_3$ is in a spin-frozen state at temperatures above the ferromagnetic transition point. A strong redshift with increasing $J$ of the peak in the real frequency dynamical susceptibility indicates a dramatic suppression of the Fermi liquid coherence scale as compared to the bare parameters in cubic BaRuO$_3$. The self-energy also shows clear deviation from Fermi liquid behavior that manifests in the single-particle spectrum. Such a clean separation of energy scales in this system provides scope for an incoherent spin-frozen (SF) phase that extends over a wide temperature range, to manifest in non-Fermi liquid behavior and to be the precursor for the magnetically ordered ground state.