Performance lag

Are you calling Application.DoEvents() ?
Are you creating the mesh in the loop?
Post some code too.

Yes I am calling Application.DoEvents.

No I''m not creating the mesh in the Render loop.

Sample:

''Clear the backbuffer to a blue color
m_obj3DDevice.Clear(ClearFlags.Target Or ClearFlags.ZBuffer, m_colBackColour, 1.0F, 0)

''Begin the scene
m_obj3DDevice.BeginScene()

'' Setup the world, view, and projection matrices
SetupMatrices()

'' Meshes are divided into subsets, one for each material. Render them in a loop

Dim intX As Integer

For intX = 0 To m_matMaterial.Length - 1

'' Set the material and texture for this subset
m_obj3DDevice.Material = m_matMaterial(i)

'' Draw the mesh subset
m_mshMesh.DrawSubset(i)

Next intX

''End the scene
m_obj3DDevice.EndScene()

m_obj3DDevice.Present()