We discuss the striking changes of the superconducting properties of YBa2Cu3O6.9 films to the homogeneous lattice disorder, induced by varying growth temperatures: Tc decreases with increasing disorder, while the width of the resistive transition and the normal state resistivity increase. We estimate the length scale of such disorder from the broadening Δϑ of the <005> X-ray diffraction rocking curves. The suppression of superconductivity and normal conductivity scales as Δϑ and appears for in-plane lattice coherence lengths rc≈1/Δϑ smaller than about 10 nm