Vectorize double nested for loop with indexing using another matrix

I tried to vectorize the following code:

n = 25; m = 5;
B = rand(n,n);
C = randsample(1:n,m);
Auc = zeros(1,m);
Au = zeros(1,n);
tic
for i = 1:10000
    for u = 1:n
        for c = 1:m
            Auc(c) = B(u,C(c));
        end
        Au(u) = max(Auc);
    end
    A = sum(Au);
end
t1 = toc;

The vectorize version of the code is as follows:

D = zeros(n,m);
Au2 = zeros(1,m);
tic
for i = 1:10000
    D = B(1:n,C(1:m));
    Au2 = max(D,[],2)';
    A2 = sum(Au2);
end
t2 = toc;

However, everytime I run t2 is bigger than t1. For example, t1 = 0.0086 and t2 = 0.0139.

Is there any problem with the vectorize version? Thank you very much for your help!!