Help with optimisation needed

Got some trouble with Trouble! Anyone who has played my puzzle game would notice some slowdown whenever large numbers of conveyor belts are used in a map. This is because currently I'm checking every conveyor against every moveable block every loop.

What I'd like is to be able to optimise this so I get the same effect without killing off too many clock cycles. Here's the code.

Function MoveBlocks()

	For p.pushblok = Each pushblok
		If Not p\locked
			If p\moving And p\movcnt > 0
				Select p\dir
				Case dirNorth
					nx = p\x
					ny = p\y - 4
				Case dirSouth
					nx = p\x
					ny = p\y + 4
				Case dirEast
					nx = p\x + 4
					ny = p\y
				Case dirWest
					nx = p\x - 4
					ny = p\y
				End Select
			Else
				nx = p\x
				ny = p\y
				p\moving = False
				p\movcnt = 0
			EndIf
				
			Select CheckBColl( p, nx, ny )
			Case collision
				p\moving = False
				p\movcnt = 0
			Case destroy
				Delete p
			Case conveyor
				p\x = nx
				p\y = ny
				p\movcnt = 32
			Case reset
				Return
			Default
				p\x = nx
				p\y = ny
				p\movcnt = p\movcnt - 4
				If p\tpe = 5 And p\movcnt = 0
					p\movcnt = 32
				EndIf
			End Select
		EndIf
	Next

End Function

Function CheckBColl(p.pushblok, x, y)

	If ImagesOverlap(pushgfx, x, y, Cchr, p1\x, p1\y+15)
		Select p\dir
		Case dirNorth
			If CheckPColl(p1\x, p1\y - 4)
				If version$ = "1.4"
					LoadMap "maps\puzzle" + cur_map + ".puz"
				Else
					LoadMap "maps\map" + cur_map + ".puz"
				EndIf
				nodoor = False
				Return reset
			Else
				p1\y = p1\y - 4
			EndIf
		Case dirSouth
			If CheckPColl(p1\x, p1\y + 4)
				If version$ = "1.4"
					LoadMap "maps\puzzle" + cur_map + ".puz"
				Else
					LoadMap "maps\map" + cur_map + ".puz"
				EndIf
				nodoor = False
				Return reset
			Else
				p1\y = p1\y + 4
			EndIf
		Case dirEast
			If CheckPColl(p1\x + 4, p1\y)
				If version$ = "1.4"
					LoadMap "maps\puzzle" + cur_map + ".puz"
				Else
					LoadMap "maps\map" + cur_map + ".puz"
				EndIf
				nodoor = False
				Return reset
			Else
				p1\x = p1\x + 4
			EndIf
		Case dirWest
			If CheckPColl(p1\x - 4, p1\y)
				If version$ = "1.4"
					LoadMap "maps\puzzle" + cur_map + ".puz"
				Else
					LoadMap "maps\map" + cur_map + ".puz"
				EndIf
				nodoor = False
				Return reset
			Else
				p1\x = p1\x - 4
			EndIf
		End Select
	EndIf

	For b.pushblok = Each pushblok
		If b <> p
			If ImagesOverlap(pushgfx, b\x, b\y, pushgfx, x, y)
				Return collision
			EndIf
		EndIf
	Next

	For pn.panel = Each panel
		If ImagesOverlap(pushgfx, x, y, tiles, pn\x, pn\y)
			If Between(x - pn\x, -6, 6) And Between(y - pn\y, -6, 6)
				If pn\tpe = p\tpe
					p\locked = True
					p\x = pn\x
					p\y = pn\y
					pn\active = True
					Return True
				EndIf
			EndIf
		EndIf
	Next
	
	For s.specialzone = Each specialzone
		If ImagesOverlap(pushgfx, x, y, special, s\x, s\y)
			Select s\tpe
			Case spHole, spHole2
				If Between( x - s\x, -12, 12 ) And Between( y - s\y, -12, 12 )
					an.animfx = New animfx
					an\x = s\x
					an\y = s\y
					an\clr = p\tpe
					an\tpe = animFall
					Return destroy
				EndIf
			Case spIce
				If p\tpe = 6
					If between( x - s\x, -16, 16 ) And between( y - s\y, -16, 16)
						Delete s
					EndIf
				Else
					If x = s\x And y = s\y
						p\movcnt = p\movcnt + 32
					EndIf
				EndIf
			Case spHeat
				If p\tpe = 5
					If Between( x - s\x, -16, 16 ) And Between( y - s\y, -16, 16 )
						DeleteSmoke( s\ID )
						Delete s
					EndIf
				EndIf
			Case spConv
				If x = s\x And y = s\y
					p\moving = True
					p\dir = s\dir
					Return conveyor
				EndIf
			End Select
		EndIf
	Next
	
	For d.doorway = Each doorway
		If d\reset = 0
			If ImagesOverlap(pushgfx, x, y, door, d\x, d\y)
				If Between( x - d\x, -6, 6 ) And Between( y - d\y, -6, 6 )
					If d\anim = 0
						p\locked = True
						d\anim = danimDrop
						p\x = d\x
						p\y = d\y
						Return collision
					EndIf
				EndIf
			EndIf
		EndIf
	Next

End Function

Thanks in advance guys.