One subtle change which seems to be introduced in warlords is that city mainteinance is increased.
I'm playing as churchill and at midgame with 7 cities and all courthouses built i can not sustain a research over 50%.
In civ4 with 7 cities in midgame i couldn't sustain a 100% research but i could sustain without deficit a research at 70% or 80%.
So it's just me or do you have also the same impression that city mainteinance is a lot increased?

Your research %age doesnt tell us wether its been increased or not, it just shows that, this game, at that point, your maintenance costs are a higher %age of your economy.

Maybe you expanded more, or your economy is weaker than in the other game?

No i don't think.I have expanded a bit more than needed but i have done it also in other games, but never happened to me that for example with 4 cities i had to cut my research to 60% in any Civ4 game.In all my civ game i'm careful toward my budget but i was really surprised that with all courthouses built and 7 cities i can not research anymore than 50% it never happened to me before in all civ 4 vanilla games.
Anyway i can be wrong but it doesn't seem to be.

Well they added decimal points to the end of everything (science, culture, maintenance, ect.)

so .15 here, .75 there, .35 so on and so forth add up.