CPU memory. It’s slow enough that you didn’t notice it at first. my 8 GB of CPU memory is full after the first epoch (approx.  144.000 mini-batch) and started to spill to swap. Also began from epoch 2, the network became really slow, it’s only utilizing 5%-35% GPU while in the first epoch it’s always around 90%.
I can upload the source codes with the dataset in the morning if you want