  We discuss X-ray and gamma-ray emissions from Crab-like pulsars,
PSRs~J0537-6910 and~J0540-6919, in Large Magellanic Cloud. Fermi-LAT
observations have resolved the gamma-ray emissions from these two pulsars and
found the pulsed emissions from PSR~J0540-6919. The total pulsed radiation in
the X-ray/gamma-ray energy bands of PSR~J0540-6919 is observed with the
efficiency $\eta_{J0540}\sim 0.06$ (in 4$\pi$ sr), which is about a factor of
ten larger than $\eta_{Crab}\sim 0.006$ of the Crab pulsar. Although
PSR~J0537-6910 has the highest spin-down power among currently known pulsars,
the efficiency of the observed X-ray emissions is about two orders of magnitude
smaller than that of PSR~J0540-6919. This paper mainly discusses what causes
the difference in the radiation efficiencies of these three energetic Crab-like
pulsars. We discuss electron/positron acceleration and high-energy emission
processes within the outer gap model. By solving the outer gap structure with
the dipole magnetic field, we show that the radiation efficiency decreases as
the inclination angle between the magnetic axis and the rotation axis
increases. To explain the difference in the pulse profile and in the radiation
efficiency, our model suggests that PSR~J0540-6919 has an inclination angle
much smaller than the that of Crab pulsar (here we assume the inclination
angles of both pulsars are $\alpha<90^{\circ}$). On the other hand, we
speculate that the difference in the radiation efficiencies between
PSRs~J0537-6910 and J0549-6919 is mainly caused by the difference in the Earth
viewing angle, and that we see PSR~J0537-6910 with an Earth viewing angle
$\zeta>>90^{\circ}$ (or $<<90^{\circ}$) measured from the spin axis, while we
see PSR~J0540-6919 with $\zeta\sim 90^{\circ}$.
