Hello community, I might be mistaken but I have the impression that

training RNN is very slow (and even slower on GPU)

unless you can parallelize the training using batches (which would make GPU useful again)

but this entails that sequences have a fixed length (you can use an End Of Sequence though)

=> so basically to be able to train faster you need to fix the length of the sequence which to me is a bit killing the whole flexibility of RNN being able to train on variable length sequences.
Are these assertions correct ? Am I missing something ?
Thanks a lot