Phonon calculations can be extremely time-consuming, but you could lower the computational demand by checking the amount of vacuum in the XY plane (look in the log file for the "Automatically detected repetitions" - you definitely want this to be 1 x 1 in the XY plane).
The phonon calculations parallelize very well, so that would be the other way to improve performance. If you are running this in serial, for DFT with that many atoms, I fear it can take weeks or months, to be honest.
Btw, it looks like your electrodes might be a bit short in Z (for the electronic part).
