How many items/lines are there in your "cetnosti" file?

What properties of Tree::Trie are you using or intending to use that are beneficial over a standard hash? I ask because in a couple of inconclusive quick tests, Tree::Trie seems to use ~twice as much memory as a standard hash to store the same information.

It also looks to me as if you are not using Tree::Trie correctly anyway. You appear to be running the key and value elements of the lookup items together into a single value and then storing them. Which if I uunderstand your purpose correctly--which is not a given as your description is far from clear--, means that you will never find anything in your input file within the tree.

All in all, I think you would be best to ask your question again. This time, post an few examples of the input data and the types of transformations that you are hoping to perform.