\[ \boxed { {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) + \left ( af \left ( x \right ) +b \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) + \left ( cf \left ( x \right ) +d \right ) y \left ( x \right ) =0} \]
Mathematica: cpu = 0.320041 (sec), leaf count = 31 \[ \text {DSolve}\left [y'(x) (a f(x)+b)+y(x) (c f(x)+d)+y''(x)=0,y(x),x\right ] \]
Maple: cpu = 0.172 (sec), leaf count = 36 \[ \left \{ y \left ( x \right ) ={\it DESol} \left ( \left \{ {\frac { {\rm d}^{2}}{{\rm d}{x}^{2}}}{\it \_Y} \left ( x \right ) + \left ( af \left ( x \right ) +b \right ) {\frac {\rm d}{{\rm d}x}}{\it \_Y} \left ( x \right ) + \left ( cf \left ( x \right ) +d \right ) {\it \_Y} \left ( x \right ) \right \} , \left \{ {\it \_Y} \left ( x \right ) \right \} \right ) \right \} \]