\[ x^4 y''(x)+\left (x y'(x)-y(x)\right )^3=0 \] ✓ Mathematica : cpu = 0.653007 (sec), leaf count = 329
\[\left \{\left \{y(x)\to -i x \log \left (-\frac {\sqrt {-8 i c_1 x^2-\sinh \left (2 c_2\right )-\cosh \left (2 c_2\right )}}{4 c_1 x}-\frac {i \sinh \left (c_2\right )}{4 c_1 x}-\frac {i \cosh \left (c_2\right )}{4 c_1 x}\right )\right \},\left \{y(x)\to -i x \log \left (-\frac {\sqrt {-8 i c_1 x^2-\sinh \left (2 c_2\right )-\cosh \left (2 c_2\right )}}{4 c_1 x}+\frac {i \sinh \left (c_2\right )}{4 c_1 x}+\frac {i \cosh \left (c_2\right )}{4 c_1 x}\right )\right \},\left \{y(x)\to -i x \log \left (\frac {\sqrt {-8 i c_1 x^2-\sinh \left (2 c_2\right )-\cosh \left (2 c_2\right )}}{4 c_1 x}-\frac {i \sinh \left (c_2\right )}{4 c_1 x}-\frac {i \cosh \left (c_2\right )}{4 c_1 x}\right )\right \},\left \{y(x)\to -i x \log \left (\frac {\sqrt {-8 i c_1 x^2-\sinh \left (2 c_2\right )-\cosh \left (2 c_2\right )}}{4 c_1 x}+\frac {i \sinh \left (c_2\right )}{4 c_1 x}+\frac {i \cosh \left (c_2\right )}{4 c_1 x}\right )\right \}\right \}\] ✓ Maple : cpu = 0.171 (sec), leaf count = 37
\[ \left \{ y \left ( x \right ) = \left ( -\arctan \left ( {\frac {1}{\sqrt {{\it \_C1}\,{x}^{2}-1}}} \right ) +{\it \_C2} \right ) x,y \left ( x \right ) = \left ( \arctan \left ( {\frac {1}{\sqrt {{\it \_C1}\,{x}^{2}-1}}} \right ) +{\it \_C2} \right ) x \right \} \]