Is the sound muffler supposed to block machine noises, like the sawmill? Because it's not for me. I had a slight bug with NEI being stuck on the last thing I searched, regardless of what I typed in the searchbox it didn't change what was displayed on the right. Restarting my client fixed it.
I've got most of the TE machines hooked up with MFR cable and tubes and I'm still getting ~60fps with items displayed, but this is on my desktop. I'll try it on my laptop and report back. It's only when I'm generating terrain or spinning in circles trying to drop my fps that it goes as low as 20.
Screenshots:
My laptop did considerably worse: no higher than 25fps after all the chunks loaded in and everything stabilized from starting up the world. I could boost that by lowering the chunk rendering, not using Faithful, stuff like that. For me anything over 20fps is playable as long as there aren't giant lag spikes as well as low frame rates.
My desktop has an i5 4690k, 16gb ram, and a gtx 480. My laptop has an AMD quad core cpu/gpu and 2gb of ram.