How to add a submatrix to a sparse matrix in parfor efficiently?

Hi,

I currently have some speed issues with a parfor loop. In the loop I calculate submatrices, which added up are the global Matrix. The code from the profiler (changed the parfor to a for loop) is below.

The submatrices are size 6x6 and consist of 4 3x3 matrices. Compared to the other computations adding these submatrices to the global matrix is extremely slow. Has andybody an idea how to speed this up?

Thank you!

 0.08  366600  49    k_l_e = auge * (f/L0(i)) + k_u; 
    50 
2.24   366600   51   k = sparse(dof,dof); 
10.37   366600   52   k_l(elementDof,elementDof) = [k_l_e -k_l_e; -k_l_e k_l_e]; 
    53 
28.70   366600  54   K = K + k_l;  end

[Arnab Sen]

Can you provide a sample code to reproduce the issue?