\[ \boxed { y \left ( x \right ) \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}-{{\rm e}^{2\,x}}=0} \]
Mathematica: cpu = 0.017002 (sec), leaf count = 47 \[ \left \{\left \{y(x)\to \left (\frac {3}{2}\right )^{2/3} \left (c_1-e^x\right ){}^{2/3}\right \},\left \{y(x)\to \left (\frac {3}{2}\right )^{2/3} \left (c_1+e^x\right ){}^{2/3}\right \}\right \} \]
Maple: cpu = 1.092 (sec), leaf count = 50 \[ \left \{ -{1\sqrt {y \left ( x \right ) \left ( {{\rm e}^{x}} \right ) ^{ 2}}{\frac {1}{\sqrt {y \left ( x \right ) }}}}+{\frac {2}{3} \left ( y \left ( x \right ) \right ) ^{{\frac {3}{2}}}}+{\it \_C1}=0,{1\sqrt {y \left ( x \right ) \left ( {{\rm e}^{x}} \right ) ^{2}}{\frac {1}{\sqrt {y \left ( x \right ) }}}}+{\frac {2}{3} \left ( y \left ( x \right ) \right ) ^{{\frac {3}{2}}}}+{\it \_C1}=0 \right \} \]