My code takes so long to execute

My code works fine until it gets to this block. This loop takes too long to execute. Is there any way to solve this problem?

if ~exist('nworkers','var'), nworkers = 0; end % default nworkers to zero
r1 = rad(1);
parfor (i = 1 : numel( kru ), nworkers)
    jlu(:,i)  =  sbesselj ( lkr, kru(i) );
    djlu(:,i) = dsbesselj ( l, kru(i) );
    if ru(i) > r1
        hlu(:,i) = sbesselh ( lkr, kru(i) );
        dhlu(:,i) = dsbesselh ( l, kru(i) );
    end
end

[per isakson]

Did you use Preallocation for jlu, djlu, hlu, etc.?

[Image Analyst]

How long is "long"?