Inacceptable slowdowns when using bufferGeometry tag

[Draco112358]

Good afternoon,
In my project I'm using a bufferGeometry tag to represent meshes with bufferGeometry, like that:

export const Composite: FC<CompositeProps> = ({ entity }) => {
    let compositeMesh = useMemo(() => meshFrom(entity), [entity.baseElements])
    return (
        <>
            <bufferGeometry>
                <bufferAttribute attachObject={["attributes", "position"]} itemSize={3}
                                 array={compositeMesh.geometry.attributes.position.array}
                                 count={compositeMesh.geometry.attributes.position.array.length / 3}/>
            </bufferGeometry>
            <meshBasicMaterial color={entity.color}/>
        </>
    )
}

Basically, I calculate the mesh using the meshFrom function, holding the returned value with useMemo, then I pass this component as children in the parent one:

...
<>
                <Transformations orbit={orbit} keyComponent={keyComponent} position={position} rotation={rotation} scale={scale}>
                    <mesh ref={meshRef} >
                        {children}
                    </mesh>
                </Transformations>
                <DetectCollision canvas={canvas} entity={findComponentByKey(canvas, keyComponent)} />
            </>

Now, anytime the parent rerenders, I experiment slowdowns, as if the Composite always recomputes the bufferGeometry, even when it does not change.

Instead, if I use directly a primitive tag like that:

... 
 let mesh = useMemo(() => meshFrom(entity), [entity.baseElements])
<>
                <Transformations orbit={orbit} keyComponent={keyComponent} position={position} rotation={rotation} scale={scale}>
                   <primitive object={mesh} />
                </Transformations>
                <DetectCollision canvas={canvas} entity={findComponentByKey(canvas, keyComponent)} />
            </>

then there are no slowdowns.

Can you explain me the difference? In both cases I represent a mesh I've already computed earlier.
I've used the profiler and it turned out that indeed the Composite component spends so much time for rerenders.

Hope someone can help me.
Thank you!

[drcmda]

that is too little information. i dont know what meshFrom is nor if entity.baseElements is stable. it seems weird to inject geometry like that. why not <mesh geometry={someGeometry}>?

[Draco112358]

meshFrom is a function that takes data from redux store (the entity) and creates a mesh from that. I've many base components so I created a parent Component that handles the tag, common to all of them. That is why I cannot use <mesh geometry={...} /> directly in the base components like Composite. The meshFrom function is stable, i've already tested it, in fact using the tag passing the same mesh calculated, I've no slowdowns. Maybe the bufferGeometry tag recreates the bufferGeometry everytime, even if the props passed remain the same. What do you think?

[drcmda]

something must trigger it, my money is on useMemo(..., [entity.baseElements])

[Draco112358]

I use the same useMemo with the and it work much better

[Draco112358]

Sorry! Reviewing my test I've found that in some cases the function meshFrom is recomputed and that is why then I got slowdowns. Thank you so much for your advice!