Speed drop when rotating

Hi its me again,

i just noticed that a scene that usually runs at ~30fps slows down tremendously when rotating a few entities.
I this example only 5 spheres are rotated and the fps drops from 32 to 8 on my office computer.

Strict

Import "../MiniB3D.bmx"
Type TSun
Field PIVOT:TPivot
Field MESH:TMesh
Field LIGHT:TLight

Function Create:TSun()
	Local tmp:TSun = New TSun
	tmp.PIVOT = CreatePivot()
	tmp.MESH = CreateSphere(8,tmp.PIVOT)
	tmp.LIGHT = CreateLight(2,tmp.PIVOT)
	tmp.LIGHT.LightColor(230,20,20)	
	Return tmp
End Function
End Type

Local width=640,height=480,depth=16,mode=0

Graphics3D width,height,depth,mode

HideMouse()
AmbientLight(50,50,50)

Local cam:TCamera=CreateCamera()
cam.PositionEntity(0,0,-10)
cam.CameraZoom(2)

Local tex:TTexture=LoadTexture("media/test.png",1)
Local tex2:TTexture=LoadTexture("media/sand.bmp",1)

Local Sun:TSun = TSun.Create()
sun.MESH.EntityTexture(tex)
sun.MESH.EntityFX(1)
Sun.MESH.ScaleEntity(3,3,3)
Sun.PIVOT.PositionEntity(0,0,20)

Local spherearray:TMesh[5]
For Local i% = 0 Until 5
	spherearray[i] = CreateSphere(16)
	Local vx:Float,vy:Float,vz:Float
	Local pos:Float = Rand(0.0,360.0)
	vx = 0 + 10 * Cos(pos)
	vy = 0 
	vz = 20 + 10 * Sin(pos)
	spherearray[i].PositionEntity(vx,vy,vz)
	spherearray[i].EntityTexture(tex2)
	'spherearray[i].EntityColor(230,20,20)
Next

' used by camera code
Local mxs#=0
Local mys#=0
Local move#=0.5
MouseXSpeed() ' flush
MouseYSpeed() ' flush

' used by fps code
Local old_ms=MilliSecs()
Local renders
Local fps

While Not KeyDown(KEY_ESCAPE)		

	If KeyHit(KEY_ENTER) Then DebugStop


	For Local j% = 0 Until Len(spherearray)			'COMMENT THIS OUT TO SEE SPEED INCREASE DRASTICALLY
		spherearray[j].RotateMesh(0,1,0)			'
	Next											'
	
	'' control camera
	
	' mouse look
	
	mxs#=mxs#+(MouseXSpeed()/5.0)
	mys#=mys#+(MouseYSpeed()/5.0)

	RotateEntity cam,mys#,-mxs#,0

	MoveMouse width/2,height/2
	MouseXSpeed() ' flush
	MouseYSpeed() ' flush

	' move camera forwards/backwards/left/right with cursor keys
	
	If KeyDown(KEY_W)=True Then MoveEntity cam,0,0,move# ' move camera forward
	If KeyDown(KEY_S)=True Then MoveEntity cam,0,0,-move# ' move camera back

	If KeyDown(KEY_A)=True Then MoveEntity cam,-move#,0,0 ' move camera left
	If KeyDown(KEY_D)=True Then MoveEntity cam,move#,0,0 ' move camera right
	
	''
	
	'TurnEntity cube,0,1,0

	RenderWorld
	renders=renders+1

	' calculate fps
	If MilliSecs()-old_ms>=1000
		old_ms=MilliSecs()
		fps=renders
		renders=0
	EndIf
	
	Text 0,0,"FPS: "+String(fps)
	Text 0,20,"Light: " +Sun.LIGHT.EntityX(True)+", "+Sun.LIGHT.EntityY(True)+", "+Sun.LIGHT.EntityZ(True)
	Text 0,40,"Mesh : "+Sun.MESH.EntityX(True)+ ", "+Sun.MESH.EntityY(True)+ ", "+Sun.MESH.EntityZ(True)
	Text 0,60,"Pivot: "+Sun.PIVOT.EntityX(True)+", "+Sun.PIVOT.EntityY(True)+", "+Sun.PIVOT.EntityZ(True)	

	Flip

Wend
End

Am i doing something wrong? Because if i am not i just can't imagine populating a real scene with entities.