RevolutionDCM runs at about 1/2 the speed of default BtS. So if it's noticeably slow, the best thing to do is turn down the mapsize. My computer sucks, and I have to play on standard sized maps or smaller. I can play default BtS on large maps, and it's about equivalent speed.
Most of that slowdown in RevDCM is caused by BetterAI and the extra processing that takes, and some of the BUG stuff, namely Plot List Enhancements, though there is some other stuff in there that makes it a little slower then BetterAI and BUG, mainly a couple python callbacks. Thankfully the upcoming version (should be released in a few days) has been built for speed, and should play at about the same speed as standard BtS; this is mainly due to the inclusion of the CAR mod. Still though, if RevDCM is running too slow for you, that means your computer is old, and you're trying to play on too large of maps for your system. You'll also probably notice slowdown from BUG, but you can get rid of that by turning off plot list enhancements. You'll definatly think BetterAI is too slow. Most mods use BetterAI, so if that's an issue not much you can do but get more RAM or a better graphics card and play on a smaller map.
Of course all that assumes you're using RevolutionDCM, and not one of the mods that use it as a base. I can only vouch for the performance of LoR, and RevolutionDCM itself, as I know how RevDCM itself handles and LoR has been built with performance in mind. LoR is about the same speed as pure RevolutionDCM; this is because there are no added python functions (everything I've added is dll stuff) and most importantly all the art has polygon and texture sizes around where default BtS's are. Most mods aren't as rigerous about the optimization of the included art, and many mods have units running around with 10,000 polygons and 1012 size textures (BtS units hover around 1000 polys and none except the War Chariot go over 2K polys, and the standard texture size is 256). So if you're running a RevDCM merge and having these problems, you can try Pure RevolutionDCM or LoR. If you're talking about RevDCM pure and it's too slow for you, you can try waiting a few days for 2.6 to come out. 2.6 will noticeably speed up RevDCM, in testing it's about at the same level as BtS is. Also you might think about getting more RAM, Civ is an old game and if RevDCM is playing too slow for you, your computer likely needs an upgrade.
BUG is just BtS with an improved interface. Read the OP, he's looking for a mod that adds some stuff, but not too much. I don't think a little Great Person bar is really expanding the gameplay. It's good, it's included in RevDCM for a reason, but it's
BtS Unaltered Gameplay, ie it's just BtS with a new UI.