Well its mostly searching through NEI thats laggy. The game itself doesn't seem to lag too much. And hopefully NEI will have mod-based searching again soon.
Seems like everything is made from machine casings now and cables. LOTS of cables.
Pistons are used in the recycler btw.
When I go up to machines, it seems to lag as well. Not even touching them, just going near them.
Edit: I lie. When I put my cursor over a tile-entity, lag spike really badly.