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It looks to me like most of the work in a view query happens in View::updateQueries. In particular, it uses std::lower_bound and std::upper_bound to find the desired ranges by searching over a timestamp index. My C++ reference states that these are binary searches, with O(log N) complexity. If you look in Bag::doWrite, you can see this index being updated as new data is written to the bag file.
The other question you reference addresses time to load a bag-file from disk, but not time to seek within that bag file once loaded. I haven't tested it, but (at first glance) it looks like view queries should be fairly quick, even in large bag files.
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