My analysis of LastPass (correct me if I'm wrong): if your master LastPass password is unique to that site, you are likely safe, but if it's one that you've reused on other sites (check http://haveibeenpwned.com), then you should be very worried.
LastPass password cracking rate on the order of 100k/sec, what various sources tell me. Given the complexity rules for passwords, you are safe from brute forcing. There is some small danger from mutated dictionary attacks, but still adversaries can try only a few billion.
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@ErrataRob 100k/sec global? per one standard CPU? or per some other amount of hardware?
@robryk Roughly per GPU.