In this question When syncing Monero's blockchain from scratch, why does it begin fast and end slow? the answers refer to validation and verification.
I've looked into Task Manager and for all Monero processes it keeps displaying 0% CPU usage, so it does not seem to be validating blocks.
Can there be other reasons? Something like bigger blocks, less seeders or daytime?
Since my data.mdb now is ~25GB and the blockchain.raw that I could have downloaded and imported instead is ~27GB, I wonder why the FAQ states that the fastest way to synchronize is from scratch using the wallet. It's missing just 2 GB and almost nothing happens.