Inefficient wavedec implementation?

Hello,

I use the wden function for denoising large signals(10M points) and I would like to reduce the execution time. By profiling, I oberved that 50% of the time is spent in wavedec and more than 25% is spent in waverec:

Turning my attention to wavedec, I observed that 50% of the runtime(so 25% of the total wden runtime) is spent in a line that is appending detail coefs to an array that was not preallocated in the code.

I suspect that the appending uses some sort of preallocation in the back(grow by factor of ... ?), but it might not be optimal.

Is there a possibility to prealocate this array(maybe based on the length of the signal and the level of decomposition)?

Thank you,

Iulian