I'm finding TMIT's assessment to be correct, and I'm basing this off of my current campaign as the Byzantines. Despite having powerful mounted units with siege alongside them, it's taking forever to capture even a few cities. And my economy has tanked during the war, which I ultimately ended because my research has plummeted to unacceptable levels. Now, in previous games, I've found Classical and Renaissance or Industrial warfare to be conducted more quickly.
Then again, I'm also a poor Civ player, so I may not know what I'm talking about.
No, I think that's a fair assessment. However, for mounted wars siege is often too slow. If you were lucky enough to get a great spy, espionage works better than siege with fast units. I also tend to wait for Cannons and then Rifles to pound the world into submission.
I also seem to find more necessary buildings in that era. If I have extra production there are some very nice wonders. As a consequence I build less military.