I’m sharing my knowledge in general on this subject. I’m pretty sure this is accurate, I might be missing a few details, but this is essentially what it is (parenting is best).
Welding creates lag in motion, no matter how you do it. Weld to base, weld to each other…the engine still calculates the mass of the prop, its relation with constrained props, potential collisions, etc. Bottom line, the physics model of the prop is carried along. You can reduce the load, for instance by only welding to base prop, but the engine still calculates the flexing of the welds and their inertia, loadings, deformation by pressure, etc. For those of us who understand construction stuff, welding is like spotwelding. The material still flexes, bends, etc.
Polyweld creates little lag in motion, as it actually fuses the physics models together. I don’t know a WHOLE lot about it, but it seems to actually fuse the physics models, into one giant “superprop”. It’s rather new, so it will glitch, it will screw up, fuck up duping, and crash, at least a percent age of the time enough to be a nuisance. Polyweld is like a casting, rather than a spotweld–the material is now fused into a single, homogeneous form, and is extremely resistant to deformation.
Parenting does *not *create lag while in motion. Parenting creates a “hull” of the prop, which we see, and which functions as armor, but the actual collision model is removed from play, usually left sitting wherever the contraption was spawned. If the collision models are right-click nocollided, they are removed from play. They do not collide with anything but world, and on the world they sit there, static (and lagless). Therefore, parenting creates very little lag. It does NOT allow you to physgun the prop, but you can weld simple invisible physics props over it or (as I do) have a base prop that roughly matches a collision model. The only downside is you MUST parent to a wire entity; parenting to a regular prop fucks it up. Parenting is reliable and does not change with spawning, unlike polyweld (which can glitch) or welding (which erodes in strength). Parenting also has the benefit that you can remove your “bodywork” and work on your chassis by moving the wire thing it’s parented to, then replace the body. It also creates no weight, so much less stress on your drivetrain & suspension.
The amount of lag I get from a 40-prop welded contraption is greater than a 400-prop parented contraption. This is not an exaggeration. Pure welding = fail. Kyle’s 1100-prop camero probably has less lag than one of my 2007 Gcombat tanks.
Something I found here on FP and decided to reupload:
[editline]21st February 2011[/editline]
a few flat plates is enough for most interiors’ physics models.