Why do the Profile Rating takes time to get updated?

[omirodricks]

I was good enough to maintain my rating at 5.00. So recently, a client of mine gave me a false rating of 4.0, which resulted in dropping my rating instantly to 4.9 in my profile. after that, I tried my best to get 5stars by providing the best services possible and I have successfully gained four (4) 5star ratings. But its been a week since that happened. But my profile rating didn't even update instantly. While I tried to contact Fiverr support, they told me it may take two weeks to settle down. But my question here is, why is the system work this way?? I mean, is this even fair?? When you are getting low ratings, your profile rating is dropping instantly, and while you are trying to fix it, it takes more time than usual. 

Oh My orders has been also dropped after this incident. Impression, clicks everything is falling apart. I need proper explanation from you guys. Please help me. TIA