Why do blockchain downloads get slower towards the end?

[MessyCoin]

Seems like most coins will load 80-90% of their blockchain very quickly for me then take ages to download the last 10-20%.

I hope someone can explain why this is? ...or am I imagining it?

EDIT: duh! I think I realized the answer: it's because there are more transactions in recent blocks and this takes longer to download/process.