Question: Numerical Integration

have some problem with Numerical Integration this function:

 > f221 := (0.1255914626e-2*(375.*sin(2.*a)*cos(b)*cos(w)-150))*Heaviside(abs(375.*sin(2.*a)*cos(b)*cos(w)-375.*sin(a)^2*sin(b)*sin(w))-150.)*sin(a)*cos(b)^3*sin(w)*(1.+.25*cos(2.*b));

> evalf(Int(f221, [a = 0 .. 2*Pi, b = 0 .. (1/2)*Pi, w = 0 .. 2*Pi], method = _cuhre, epsilon = .1)) 

How can i take this integral and  decrease calculation's time? I was trying different method, and its couldnot be taken every time. 

Thank! 

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