Perhaps you should also go to this website
https://www.grc.com/haystack.htm and input a password of the same length and character type (although not obviously your exact password) into the box to see somerought stats on how difficult it is to be brute-forced. Not too difficult I would imagine, and now remember that some in this community will have GPU farms not mining much BTC anymore, which could possibly earn more in more 'malicious' ways...
Those estimates are usually worthless.
The encryption in bitcoin-qt's wallet uses powerful strengthening— on your own system it won't be able to test more than 10 attempts per second... even with a powerful GPU farm things will be limited.
(as compared to BC.i wallets, for example, which has gpu cracking tools that do millions of attempts per second)
That isn't to say that having a good key is important— it is... but for many people the strengthening is enough that the bigger risk is losing/forgetting the keys.
I know nothing about this really, apart from what I have read on the interwebs, but I would be worried that there might be a (custom?) other program/software which could be used to decrypt the wallet file faster than Bitcoin-Qt? Or is the slow cracking speed simply a result of the encryption protocol used?
