Vk = V(x) + VH(x);
Wk = zeros(N);
tic;
for k1=1:N
    Wk(k1,k1) = w * (B(k1,:).^2 .* Vk.').';
    for k2=k1+1:N
        Wk(k1,k2) = w * (B(k1,:) .* Vk.' .* B(k2,:)).';
        Wk(k2,k1) = Wk(k1,k2);
    end
end
fprintf('Referenz: %s\n', szeit(toc));

% eine for Schleife
Vk1 = diag(w' .* (V(x) + VH(x)));
Wk1 = zeros(N);
tic;
for k1=1:N
    Wk1(k1,:) = B(k1,:) * Vk1 * B.';
end
fprintf('mit Diagonalmatrix:     %s    ', szeit(toc));
serr(Wk, Wk1);

Vk2 = (w' .* (V(x) + VH(x))) * ones(1,N);
Wk2 = zeros(N);
tic;
for k1=1:N
    Wk2(k1,:) = B(k1,:) * (Vk2 .* B.');
end
fprintf('mit erweiterter Matrix: %s    ', szeit(toc));
serr(Wk, Wk2);

whos Vk1 Vk2;