\[ \boxed { \left ( \left ( y \left ( x \right ) \right ) ^{2}+{x}^{4} \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -4\,{x}^{3}y \left ( x \right ) =0} \]
Mathematica: cpu = 0.014502 (sec), leaf count = 53 \[ \left \{\left \{y(x)\to \frac {1}{2} \left (c_1-\sqrt {c_1^2+4 x^4}\right )\right \},\left \{y(x)\to \frac {1}{2} \left (\sqrt {c_1^2+4 x^4}+c_1\right )\right \}\right \} \]
Maple: cpu = 0.234 (sec), leaf count = 67 \[ \left \{ y \left ( x \right ) = \left ( {\frac {1}{2\,{x}^{2}} \left ( 2\, {x}^{2}+{\it \_C1}-\sqrt {4\,{x}^{4}+{{\it \_C1}}^{2}} \right ) }-1 \right ) {x}^{2},y \left ( x \right ) = \left ( {\frac {1}{2\,{x}^{2}} \left ( 2\,{x}^{2}+{\it \_C1}+\sqrt {4\,{x}^{4}+{{\it \_C1}}^{2}} \right ) }-1 \right ) {x}^{2} \right \} \]