Hi Anna,
That sounds reasonable for that chip.
If you want a faster response then you need to look at the thermal setup - using the thermal pad on the chip and perhaps forcing air past it if you are measuring air temperature. No matter what you do with it, however, you're limited by the thermal capacitance and resistance of the device - if you need a much faster response then you'll need to use a different type of sensor,
All the best,
Alan