In the Baseline section, you will find a sentence with the following: "However, there is a cost to using the strategies. We have to run all of the sentences through the bag-of-words model first, to determine if we should use the bag-of-words or the LSTM." followed by some math that takes the added cost into account, which is also what we based our plots/results on.
It was based on test time prediction, so given you have received a sentence, how fast does it take to compute the prediction with either a bag-of-words or an LSTM.
When you say practical example, would that be in the scenario that you have an API server running? So to consider such costs as latency, data transfer, API overhead etc.?