Nimes - Montpellier bypass starts construction late this year, due to open Dec 17 TT. This despite the RFF website saying it is due to open his year! Think it knocks off 15 mins, about 5 of which is by not stopping at Montpellier.
Montpellier - Perpignan is in very early stages of planning. Current forecast date is 2020, but you can add at least 4 years to that, as there has not been 'public debate' yet. This will take off at least a further half an hour, more if Narbonne is bypassed.