To dream that something is too heavy, symbolizes your burdens, work load and responsibilities. You are carry too much on your shoulders and need to prioritize. Take a break and lighten up.
Something heavy or dense can represent:
Seriousness or solemnity
Full of meaning, richness, or some other attribute
A burden, or a feeling of being burdened
Great substance or strength
Great significance, as in a weighty matter
An obstacle