I know Steve's Factory Manager can cause issues. On my server one day the tps was just really low and I couldn't find the source of the tps drop through OPIS. Then I noticed a harvestcraft presser that had an unusually high update time. Turns out it was a Steve's factory manager setup that was causing the tps drop because it was on a chunk boundary. I think as long as your setup is within the same chunk and isn't performing tasks super fast, it should be fine. I know quite a few people who have been using Steve's Factory Manager and our TPS has been stable at 20 for a while.
Also regarding The Spice of Life if you eat certain fruits (from Natura), then you can easily bypass The Spice of Life diminishing returns because they still give a half point of hunger even if you've eaten them 6 out of 6 times
. I usually eat those fruits 6 times and then eat something out of my lunchbox to fill my hunger back up really fast.