Use python read for text dataset
One thing though, could we try to read the files in parallel? We could but I'm not sure this would help a lot since the bottleneck is the drive IO if the files are big enough.
It could make sense for very small files. Looks like windows is not a big fan of this approach
I'm working on a fix I remember issue https://github.com/huggingface/datasets/issues/546 where this was kinda requested (but maybe IO would bottleneck). What do you think? I think it's worth testing multiprocessing. It could also be something we add to our speed benchmarks > I remember issue #546 where this was kinda requested (but maybe IO would bottleneck). What do you think?

It still would be interesting I think, especially in scenarios where IO is less of an issue (SSDs particularly) and where there are many smaller files. Wrapping this function in a `pool.map` is perhaps an easy thing to try.  Merging this one for now for the patch release
As mentioned in #622 the pandas reader used for text dataset doesn't work properly when there are \r characters in the text file.

Instead I switched to pure python using `open` and `read`.
From my benchmark on a 100MB text file, it's the same speed as the previous pandas reader.