19 out of 24 words of BIP39 passphrase (brute-force last 5?)
You have three options here:


Using a GPU implementation of the Gurnec´s Seed Recovery script
Use Hashcat / JTR, where PBKDF2-HMAC-SHA512  is already implemented.
Use brainflayer, similar to Gurnecs software, no multithread, no GPU.


Gurnec´s script runs at aproximately 40kh/s under my i7-8700k without OC. So if you only had lost the last 4 words of your seed, it will be 2^36 hashes.

2^36 h / 40.000 h/s = ~ 20 days

So it will take roughtly 3 weeks to test every combination.

But to crack the last 5 words of your seed it would take 2048 * 20 days.

On the other side according to the benchmarks PBKDF2-HMAC-SHA512 hashes at a 4.800 kh/s under a usual 8 x 1080´s rig so it should be possible to recover in several days the 5 missing words.

tldr; Implement GPU in btcrecover or brainflayer or understand how to make it work under Hashcat. Up to 3 words + checksum word doable in CPU, more need GPU.