  Swift J1357.2-0933 underwent an episodic accretion in 2011 and provided very
regular temporal and spectral evolution, making it an ideal source for
exploring the nature of very faint X-ray transients (VFXTs). In this work, we
present a detailed analysis on both X-ray and near-ultraviolet (NUV) light
curves. The fluxes at all wavelengths display a near-exponential decays in the
early phase and transits to a faster-decay at late times. The e-folding decay
time-scales monotonically decrease with photon energies, and the derived
viscous time-scale is $\tau_{\rm \dot{M}} \sim 60$ days. The time-scale in the
late faster-decay stage is about a few days. The high ratio of NUV luminosity
to X-ray luminosity indicates that the irradiation is unimportant in this
outburst, while the near-exponential decay profile and the long decay
time-scales conflict with the disc thermal-viscous instability model. We thus
suggest that the disc is thermally stable during the observations. Adopting the
truncated disc model, we obtain a lower limit of peak accretion rate of $0.03
\dot{M}_{\rm Edd}$ and the X-ray radiative efficiency $\eta < 5\times10^{-4}$,
which decreases as the luminosity declines. The low X-ray radiative efficiency
is caused by the combined action of advection and outflows, and naturally
explains that the X-ray reprocessing is overwhelmed by the viscous radiation of
the outer standard disc in the NUV regime. We also propose a possibility that
the outer standard disc recedes from the central black hole, resulting in the
faster-decay at late times.
