The lag only happens with the hollow carrages in this manner, and doesn't become apparent unless alot of them are set up in this manner.
To help explain the pic above, what is happening is that an annilation plane and an AE2 cable are both inside the hollow carrage (being the annilation plane is a multipart, it will fit inside the hollow carrage, a VERY nice feature, lol).
Due to the size of the annilation plane, and the size of the hollow carrage, the gfx of each "glitch" through each other, and results of the pic above. The frames are not moving in that pic, they are standing still.
As long as the frames are not moving, nor the player, there is no lag, but as soon as either the player, or the frames, or both start moving, then the lag hits from the visual glitching of one item rendering on top of another.
At least, I am assuming that is causing the lag. In any other instance/usage of the frames, there is no lag unless a large frame machine is made/moving, but that is to be expected.
As a test, could try modeling the hollow carrages one pixel smaller, as so not to be a full block size if that makes sense, and test to see there are still similar lag issues.
Also, this is probably a "rare case of a block/mod being used in an unusual manner causing unatended effects and should not be used in this manner" type of situation.