I don't have "not excessively" and "a lot" on my ruler.
How many, and how many Mb each, or pixels x pixels.
Do you have wrap set on floating objects and are they interacting with each other and the text?
Have you applied lots of effects like borders, frames, shadows, reflections etc.
What I am asking is are you making Pages do a lot of work to lay out the document and calculate the text flow through the document?