Yes it does take a while for all the words to load (I've got a SSD).
The searching is much quicker when loaded in RAM rather than on the hard drive so that is the reason for this.
Don't put in end as that is the word that I used to stop execution.
At the prompt put in .2334.4n52.54 (this was an actual example from a "sunday telegraph" puzzle)
the string indicates that there is a "N" in the middle (a known letter)
positions 2 and 9 are the same letter, positions 3 and 4 likewise 5,7 and 13 are the same 9 and 12 are also the same.
The dots represent single unknown letters.
In the actual codeword the numbers were 13,8,21,21,4,16,4,n,3,8,10,3,4 and this is also accepted as input.
Both will give just one word differentiate, which may be enough to solve (with a bit of thought) the whole puzzle.