RR is also in BETA. The process of pruning the pack is already underway. Also if you have Underground Biomes installed I'd uninstall that since its terror on system resources.
But to be honest, Resonant Rise in 1.6 is just one of the heralds of future modded minecraft packs. Lower systems are going to take a pounding. That's just the law of technology. Personally I've enjoyed a marked improvement in performance between 1.5.2 RR and 1.6.4. My PC is 4 years old and has a very cheap graphics card yet I maintain +50fps
Yeah. i saw on the G+ group. looking forward seeing what is going to be pruned away from the pack. my system is not a lower end system however. it's only about 3 years old, and it was built custom for gaming too, altho i am a bit light for RAM. I had one of my RAM cards burn out on me, so i just pulled it out without replacing it with a new one, gonna build a new rig fairly soon i think tho. or just get new RAM and a pair of disks, this rig can still do most games decently, even gfx intensive ones.
tbh. the only mods i really do feel a direct need for, is TiCo,IC2,TC4,BC,railcraft, and forestry/MFR.(don't need both, altho i have a hard time choosing between them). Mods i don't mind, but tend not to use is the UE series, probably due to unfamiliarity more than anything else. mekanism is, I have found, a decent alternative to IC2 tho.
myst,twilight forest/other extradimensionals are fine, they usually are very optional, and are easy to ignore when you don't care to use them. altho i like to have them around in case the mood strikes me. same for biome mods, altho i didn't find the underground biome mod to really add big value, so that one is indeed going away from my system next time i try it out. (prolly tomorrow, i do want to try out ars magica, the new system looks damn cool)
there are also a lot of mods i would probably miss if they weren't there, but whose items i rarely think about as coming from separate mods. that list is probably much longer, and i would miss them if they went away.
then there were the mods i really just didn't like, like minechem,agriculture, metallurgy and minegica. they added a lot of stuff, that really weren't useful to me, (or that i didn't like the mechanics for),and thus just added useless items to the world. especially metalurgy with it's orespam annoyed me a lot. they are kinda useless when you use TiCo and MPS for all your tools/armor annyway.