Thank you very much for your reply buddy ;-)
Normally the printing speed is the same, and is very low (around 30mm/s). Also, I use PLA, but don't to which extent you can consider it flexible, but I think it is not, if you bend it too much it will break.
This is the one I use: https://www.amazon.co.uk/PrimaValue-PLA-Filament-1-75mm-Various/dp/B013K82E7K
This problem happened one or two times during the real model printing, but it happened way more during the printing of the base layer.