\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) =1/2\,{x}^{2} \left ( 1+2\,\sqrt {{x}^{3}-6\,y \left ( x \right ) } \right ) =0} \]
Mathematica: cpu = 0.096512 (sec), leaf count = 31 \[ \left \{\left \{y(x)\to \frac {1}{6} \left (-12 c_1 x^3-36 c_1^2-x^6+x^3\right )\right \}\right \} \]
Maple: cpu = 0.172 (sec), leaf count = 23 \[ \left \{ {\it \_C1}-{x}^{3}-{\frac {1}{2}}-\sqrt {{x}^{3}-6\,y \left ( x \right ) }=0 \right \} \]