Yes it does, and I tried it with lower amplifier levels. Since each loop both amplifiers produce a gain of 30 dB and the total loss is around 28 dB. That means each loop the signal is getting larger by 30 dB! The split-step fourier method, that calculates the nonlinear and dispersion effects, then needs to use many more sections to split up the fiber, which can cause a slow down for the simulation. You could also try the CUDA option in the Layout Parameters. Using CUDA, fourier transforms can be calculated quicker and in this case might improve the simulation time considerably.
Regards