My biggest problem was the speed as well, normal really wasn't that bad, but I could have gone for slower, as I tried that, EVERYTHING was so slow, as someone said already, it woulda been nicer if just the tech's were slown down... So... That's what I went and did!
If anyone would like it so their epic games only slow down the tech tree and nothing else, head to your Civ folder and go through it and get to the "Game info" XML
(C:\Program Files\Firaxis Games\Sid Meier's Civilization 4\Assets\XML\GameInfo)
Open up the "CIV4GameSpeedInfo" XML file using a simple word device (I'm just using wordpad) and here you'll see a list of stuff that looks like code. For anyone who instantly thinks "uh oh... I really shouldn't touch this", trust me, it'll be simple.
Alright, let's see what we've got here:
Woah! look at all that jibberish!

. Seriously though, it's simple - if you look at the top it says "<Description>TXT_KEY_GAMESPEED_EPIC</Description>" which means epic, it's the one we want to edit. None of this needs to make sense to you really if all you want to do is just increase the research cost and nothing else. So... look to the next quote to see what we've got.
Here we have the normal speed settings, all the info that is coded to get you what you want in the normal game. Notice - everything is set at 100 (xcept inflation), as in 100 percent, i.e. the normal rate, you can confirm this by scrolling lower to the fast game style and you see all the values have decreased again. Anyway, this is what we needed to know, just what makes a normal game normal. So what it looks like you'll need to do, scroll back up to the Epic style section and manually change all the values to 100 EXCEPT the research value.
this is the research value of an epic game - <iResearchPercent>150</iResearchPercent>
That's what you want. So actually, I've already done it myself, and here's what you should end up with:
It's tried and true folks, I've already tested it and it works, all production speeds and worker speeds are the same and technology is slower to learn. Obviously I this shouldn't be the only way we should have to do this if we want a slow game, but hey, atleast it isn't as hard as it really looks.
Lastly, you can use all sorts of values in when editing these files to COMPLETELY customize your gameplay, even how many years go by in a turn. Just by simply editing the # value.
Although you might want to save an extra copy of the original just incase, I always do.
Anyway - Hoped this helped!