I’m not quite sure what you’re asking. I take it the the training works fine in terms of that the loss goes down and the accuracy goes up, right?
You’re wondering about the performance now. 60s/epoch doesn’t mean anything without knowing the data and hardware. And that it was 10s/epoch before “some edits” doesn’t help much either. At a quick glance, your code looks fine, and you have the tutorial and the training seems to work as well. Not quite sure what you’re looking for now.
Of course, one main bottleneck is that you give the network only one sentence at a time (please correct me if I’m wrong). Using batches would speed up the training significantly.