About our "internal clock" or the "framerate" of consciousness: the characteristic speed may be the result of limitations and constraints of biochemical reactions in the brain, but it may also be the product of evolution.
Take for instance the motion of the shade cast by a tree under the sun: its motion is barely noticeable, it seems to be just under the threshold of perception, but not very much lower. Why? Perhaps it is no coincidence, there may be an evolutionary reason: if we saw it moving it would interfere with our ability to detect moving creatures under the tree!
So, perhaps the speed of rotation of the Earth is somehow responsible for the setting of a lower bond of our perception of flow of time (our "deltat"). Other things may also be factored to, such as the grow of plants.