\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) ={\frac {1}{x} \left ( {{\rm e}^{-{\frac {y \left ( x \right ) }{x}}}}y \left ( x \right ) +{{\rm e}^{-{\frac {y \left ( x \right ) }{x}}}}x+{x}^{3} \right ) {{\rm e}^{{\frac {y \left ( x \right ) }{x}}}}}=0} \]
Mathematica: cpu = 0.096012 (sec), leaf count = 30 \[ \left \{\left \{y(x)\to -x \log \left (\frac {e^{3 c_1}}{3 x}-\frac {x^2}{3}\right )\right \}\right \} \]
Maple: cpu = 0.063 (sec), leaf count = 19 \[ \left \{ y \left ( x \right ) =\ln \left ( 3\,{\frac {x}{-{x}^{3}+{\it \_C1}}} \right ) x \right \} \]