How to improve performance with a lot of meshes

Question

I'm making a Tron clone, the trail of the cycles generates a lot of vertexes every second and they never disappear.
The render is a Mesh.Primitive_triangles type, I thought it would have been easy to render but after a while the game starts to go very slow.
What are the settings of the material (spatial) that I should use? Are there other ways to improve performance?

Comments

Actually I'm using a SurfaceTool inside a MeshInstance Node.
Immediate Geometry doesn't let you create collisions from meshes, that said I' going to try reducing the amount of vertexes as you said

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Ok I'm noob and I can't fix the code myself. I created a timer for the generation of the vertexes, it has to be 0.017 seconds or less, or the trail is not rendered precisely.
A second timer creates the collision box every 0.07 seconds, it does improve performance if i increase the time, but i need the collisions to exist as soon as possible.
This is the code:

func _on_Timer_timeout():
if is_target and wr.get_ref():
    surfTool.begin(Mesh.PRIMITIVE_TRIANGLES)
    surfTool.add_vertex(prev_point1)
    surfTool.add_vertex(prev_point2)

    surfTool.add_vertex(Vector3(p.x,p.y+l,p.z))
    prev_point1 = Vector3(p.x,p.y+l,p.z)

    surfTool.add_vertex(Vector3(p.x,p.y-l,p.z))
    prev_point2 = Vector3(p.x,p.y-l,p.z)

    surfTool.add_index(0)
    surfTool.add_index(1)
    surfTool.add_index(2)

    surfTool.add_index(1)
    surfTool.add_index(2)
    surfTool.add_index(3)

    surfTool.index()

    surfTool.commit(m)
    set_mesh(m)
else:
    get_parent().queue_free()

func _on_Refresh_timeout():
get_parent().get_child(1).shape = mesh.create_trimesh_shape()

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it's not clear what you have done since we are missing what prev_point and p are, but does this work or not?
if it works, do you notice any stuttering?

ps: i dont know if that's faster, and sometimes it brokes the collision shape, but have you thought about using scale?

pps: for the timer, i would have used a simple counter, like (but i dont know which method is the most efficient tbh)

var t=0
func _process(_delta):
  t+=1
  if t>refresh_time:
     t=0
     do_stuff()

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It works, but after a while the game gets slower. I thought about resizing the mesh, but it would scale it on both directions
prev points are the previous point that I used a vertexes, and p is the position of the player

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yeah you have to scale it and move it at the same time.
strange though, if vertex count stays the same it shouldnt get worst over time