General entry visas may take less time than Tier 1s, but the ECOs processing the tier applications slow *all* applications down to a certain extent, because they're taking longer to process those visas under the new rules. The rules for other visas have stayed the same (I believe, at least for settlement visas), but they're still being affected by the tier visas all the same. I believe they're trying to get the tier visas sorted in 5-15 business days, other visas have varying times with which they can be processed (i.e. spousals can be up to 12 weeks in some cases, etc.)
And like Vicky said, it's not a straightforward application--I assume because your girlfriend has asylum status in the US, and not citizen status (if this is wrong, correct me), so it wouldn't be as straightforward as if she was a citizen.