Difficulty adjustment with BTC is based on hashrate (block generation time) over last 2016 blocks (around 2 weeks). I'm sure we'll be back to normal when BCH adjusts its difficulty up in a day or two.
wow, 2016 blocks is quite a lag then for any updates?
Yes. It helps to make sure it adjusts to the correct difficulty (if you did it over 5 blocks, the 5 blocks could take a lot longer or shorter than normal by chance).
Forks, through no fault of their own, can really harm the Nash equilibrium in BTC. As soon as they're more profitable to mine, miners have the incentive to switch to them, which could potentially decrease BTC's security by drastically decreasing the hashrate.
So far nothing dangerous has happened, but hypothetically it could be really serious.