Question: Slow summations

Hello, can somebody give some suggestions to speed up this summations? I am summing up to 10 and it take ages (about 10min).

Digits := 10;
n1 := 122;
x := 54;
n2 := 65;
y := 14;
alpha1 := 1.1;
beta1 := 1.1;
alpha2 := 1.1;
beta2 := 1.1;

Sigma2 := (j, l, psi0) -> Sum(Sum(Sum(psi0^(-y - alpha2 - l - alpha2*h - v)*pochhammer(beta2 - 1, h)*pochhammer(beta1 - 1, u)*pochhammer(y + alpha2 + l + alpha2*h, v)*2^(-y - alpha2 - l - alpha2*h - x - alpha1 - j - alpha1*u - v)*(psi0 - 1)^v/(h!*(y + alpha2 + l + alpha2*h)*u!*v!*(y + alpha2 + l + alpha2*h + x + alpha1 + j + alpha1*u + v)), u = 0 .. upto), h = 0 .. upto), v = 0 .. upto);

F2 := psi0 -> Sum(binomial(n1 - x, j)*Sum(binomial(n2 - y, l)*(-1)^(j + l)*Sigma2(j, l, psi0), l = 0 .. n2 - y), j = 0 .. n1 - x);

upto:=10;

F2(5.620);

Thanks in advance.

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