There seems to be a number of questions along the lines of:
My Bitcoin Core {bitcoin-qt|bitcoind} is slow to sync?
I have created a wiki-answer in response to one such question a while back and have found myself several times marking questions as duplicates and referring the asker to that answer. Like any answer, it can still be improved.
Nomination: Sync with bitcoin-qt very slow (0,01%) (if accepted, it may be worth considering making the question heading more all-encompassing)