A little suggestion:

What about a Pause or a kind of bounce killing?
Something like,
Code:
IF MEM_l = 2  THEN 
   WHILE MEM_l = 2 : WEND
   speed = speed + 1
ENDIF

OR
IF MEM_l = 2  THEN 
   PAUSE 100
   speed = speed + 1
ENDIF

Speed increases so fast that it goes crazy!
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