I think that XMR should change its algorithm.
My XMR blockchain was 6 days behind the network: 8600 blocks unsync-ed. It took me 40 minutes sync-ing the blockchain from 1h33 - 2h25 PM
That's a hash rate of 4/sec. Doubtful the PoW algorithm had much to do with this. What device is it?
PoW is not the only difference between BBR and XMR. Another is many more transactions on XMR. Or you may simply have been connected to slower peers.
Another difference is block interval - Monero have twice more blocks per day.