The calculation is based on what common web servers can handle: 100 sign-in requests per second.
So that is good - but you will forget that password after one minute, so you would write it down and put the note under the keyboard - where nobody would think of looking
So that makes it insecure again.
As we have suggested here before use sentences in a dialect that you will not find in any dictionary. But even if you use plain words and use three words it is extremely safe:
this is fun - as a password would take 2537 years to crack! ...And you would remember it

But wait...

Wait for it.....

du-bi-dubi-dub will take 531,885,448,467 years to brut-force!

I knew it!: Frank Sinatra was a genius

But then again the IBM Sequoia can handle 16,32 trillion floating points per second. ...So can anyone with a calculator please figure out how long it would take then?