I am writing a Java application that among other things needs to read a dictionary text file (each line is one word) and store it in a HashSet. Each time I start the application this same file is being read all over again (6 Megabytes unicode file).

That seemed expensive, so I decided to serialize resulting HashSet and store it to a binary file. I expected my application to run faster after this. Instead it got slower: from ~2,5 seconds before to ~5 seconds after serialization.

Is this expected result? I thought that in similar cases serialization should increase speed.