<s>[INST] This function seems a bit slow, likely because of the dictionary. The loop iterates 160,000 times, so any optimization would be welcome.

```
def find_word_freq_by_letter(bin_word_dict):
    word_freq_by_letter = {}
    for word in bin_word_dict:
        for letter in word:
            if letter in word_freq_by_letter:
                word_freq_by_letter[letter] += bin_word_dict[word]
            else:
                word_freq_by_letter[letter] = bin_word_dict[word]
    return word_freq_by_letter
```

Is there anything I can do to optimize this code?[/INST]