Bip39 phrase generator https://www.plurk.com/p/3hf2syltjx Let's assume it will be 10x more quickly than the GFX card higher than so roughly two,4M hashes/s. A standard attacker will personal some such specialised gadgets. For words that only have three letters, there is not any 4th letter. For example Together with the word https://hylistings.com/story21448046/bip39gen-the-5-second-trick-for-bip39-compatible-wallet-https-dzen-ru-bip39-phrase-com