Scrabble algorithm review and performance suggestions
If what you are trying to do is store a huge list of valid words in such a way that you can test whether a given string is a valid word, a Trie works well.  See this Stack Overflow question.

Load the wordlist into the Trie when your server starts, and use the same Trie for all games (assuming this is a client server game).  It's trickier than the linked thread if you need to include more than the standard 26 letters of the alphabet, but I've done a Unicode Trie for a chat filter before and I could help if you need that.

I don't understand what you are trying to do with the rearrange method.  Can you explain?