\[ \boxed { \left \{ {\frac {\rm d}{{\rm d}t}}x \left ( t \right ) =-y \left ( t \right ) ,{\frac {\rm d}{{\rm d}t}}y \left ( t \right ) =2\,x \left ( t \right ) +2\,y \left ( t \right ) \right \} } \]
Mathematica: cpu = 0.042005 (sec), leaf count = 52 \[ \left \{\left \{x(t)\to c_1 e^t (\cos (t)-\sin (t))-c_2 e^t \sin (t),y(t)\to 2 c_1 e^t \sin (t)+c_2 e^t (\sin (t)+\cos (t))\right \}\right \} \]
Maple: cpu = 0.032 (sec), leaf count = 42 \[ \left \{ \left \{ x \left ( t \right ) ={{\rm e}^{t}} \left ( \sin \left ( t \right ) {\it \_C1}+\cos \left ( t \right ) {\it \_C2} \right ) ,y \left ( t \right ) =-{{\rm e}^{t}} \left ( \sin \left ( t \right ) {\it \_C1}-\sin \left ( t \right ) {\it \_C2}+\cos \left ( t \right ) {\it \_C1 }+\cos \left ( t \right ) {\it \_C2} \right ) \right \} \right \} \]