Will parts that intersect contribute to lag?

I’m currently working on a Roblox game and have a question regarding the impact of intersecting parts on game performance. Specifically, I’m interested in understanding whether parts that intersect with each other can contribute to lag in a Roblox game.

Right now, I’m at around 15k parts and noticing flickering iykyk, between parts that intersect with one another, this is not in the view of the player btw. I would estimate there to be currently around 70-100 instances where this occurs and I’ve tried my best to cull these parts and it’s resulted to around 50 remaining.


My primary question is whether these intersecting parts, even when they’re not visible to the player, can still contribute to lag and flickering in the game. I’d like to optimize the game for a smoother player experience and would appreciate any insights, best practices, or suggestions for handling intersecting parts effectively.


I don’t think it should be an issue?
Mostly lag is related to the amount of objects in the players rendering range, as well as if they’re anchored or not (as they have to take into consideration the physics engine)

Otherwise I think you should be fine.


The flickering is due to z fighting, I suggest looking it up


Z fighting should not contribute to any kind of lag as far as I’m aware. However, stuff like shadows, unions, anchoring, decals, and textures will contribute to lag. It is common rule that you should turn CastShadow off for any parts that do not need it and to try to use meshes instead of unions unless necessary.


On the documentation for CastShadow it says it is not actually designed to help performance and only for the look if needed. BasePart | Documentation - Roblox Creator Hub

you are seeing z fighting. it causes flickering between intersecting parts that occupy the exact same area because the render doesnt know whats infront. two easy ways to fix this, either make sure no parts intersect or increase the size of the parts intersecting by 0.01 since its not longer occupying the exact same area the render knows what to render first, visually the part looks the same

lag from parts (outside of rendering, part lag from rendering is way more stuff to write) only comes from physics. so if you have those parts anchored nothing will happen

for example:
cramp 200 parts in the same area, make them all unanchored and see what happens. game lags for a bit because all the forces turned on and a ton of collisions happened

Yeah I know what’s causing it I’m just asking if it will cause lag cause I don’t wanna change everything lol

I think the lag from CastShadow isn’t actually from CastShadow. I think it’s the technology you use. I have encountered numerous times where my game became less laggy by turning CastShadow off for parts. I also really only ever use Future and ShadowMap technology, both of which have more detailed shadows and tracing on said shadows. Aka, the real issue is the rendering. I would imagine using something like Compatibility technology with CastShadow shouldn’t cause issues, but I do not know anyone who uses Compatibility, so turning CastShadow off for unnecessary parts helps.