Scientific progress is "slower" in the Empire, because the Holders, Heirs, and the Emperor are all long lived.
For an example: A variety of wheat is developed, what is the cost of using that wheat ?
It would increase the food production from the farmland, which would increase the power and prestige of the Holder who owns that farmland.
There would be increased demand for phosphates and other fertilisers, a different Holder would benefit from that, increasing their power and prestige.
The run-off of fertilisers would affect the fishing and other aspects of the environment, reducing the prestige of the Holder in the coastal areas.
The increase in population that the food would support, would affect things such as military recruitment by Imperial forces, Imperial taxation, and much more.
So, the new variety of wheat, would alter the balance of power between the planetary Holders, the planet's overall Holder, and also the relationship between other planets in the star system, constellation, region, as well as the relationship with the Imperial authorities.
And the Holders, Heirs and Emperor can see such situations arising within their lifetimes. So they are conservative in implementing some technologies.
The Empire is conservative in implementing things, but not necessarily in researching them.
And with the whole thing about newer works making older works apocryphal, then there is the thing that the Amarr religion places scripture within the context of the time.
If an old text says Pi is 3.14, and a newer text determines that Pi is 3.142, and a more recent one says 3.14159, then it does not mean the older one is apocryphal, as it is entirely righteous within the context of the time.
It may also be inspirational - "The ancient philosophers determined Pi to be 3.14, with only simple tools. Consider the difficulty of that achievement, and reflect on what is then expected of you, with modern tools."
Or something