Pipez is not the worst, but the functions people try to accomplish with systems like Pipez is inherently taxing, you will eventually encounter TPS issues with item transport mods. Mods are always updating and changing, but I believe xnet was winning out as the least laggy option in testing a year or two back. It is not as user friendly as pipez, but some of the decisions that make it less user friendly also do contribute to it's efficiency.