Is 30,000 rounds really needed for PBKDF2? In the browser, I'm using AES-256-CBC with 128bit IV &amp; PBKDF2 to encrypt the mnemonic

"tell file snow green proof evil six squeeze budget various orbit clock" 


with a password 

"s0mesuperl0ng!password@!" 


with 30,000 rounds it's taking roughly 22 seconds. It feels too long, but I don't want to make it insecure. 

Can I safely reduce the rounds to make it a bit faster? and if so what would be the minimum? 

Could I get away with 10,000?
Can I safely reduce the rounds to make it a bit faster? and if so what would be the minimum?
Could I get away with 10,000?

Anyone trying to crack your encrypted data is not going to be limited by the speed of javascript executing in a browser. They'll be running FPGAs or something much faster than that. So 20,000, 10,000 or 0 doesn't make any sort of difference here.
Where I learned this