Is this memory usage normal?
Can it be optimized？
It totally depends on your model. How many textures are in use and how big are they ?
you have 30 texture of 1024 * 1024 and 3 2048 * 2048 as seen in the inspector so
(1024102430 + 204820483) * 4 * 1.3 = 230Mb
So it is totally normal to see about 250 Mb diff on this model.