[spacious]

Push-opera is a battery drain, but people want the "cool" thumbnails on the sense internet tab. Can't have it both ways.
There's also a lot of other "automatic" internet updating turned on by default - weather, facebook, twitter, e-mail - these all use lots of battery, and RAM too.
Turning off or reducing the frequency of any or all of these will improve battery life and RAM usage as well.
A stock ROM with these features active has even worse battery life in my experience.
We all want TONS of cutting edge features with minimal battery drain and RAM usage, but it just isn't going to happen.
Energyz is a ROM chef, not some sort of magician. You still have the same battery and the same amount of RAM, in fact that and the radio are the only things that haven't changed.
My battery lasts a few days if I need it to now that I disabled most of the auto-internet and stopped playing with it all the time, without any "battery saver" cabs.
In fact I seem to get better battery life every day as the new-ROM effect wears off and my phone gets "normal" everyday usage.

A quick search (ppcgeeks, xda-dev, www) will find a wealth of tips and tricks about when and how often to charge or not charge a Li-ion battery.

Thanks Energyz.