AIR's fibo doesn't have the memory requirements of hfibo I already posted it running in a loop with a steady memory use.
My guess is that ScriptBasic isn't releasing its recursive resouces until the program ends. How other languages are storing their recursive state so efficiently is a mystery to me.
AIR has already proved SB doesn't leak.
AIR is still looking at it but isn't the fibo the SB team is recommending. Please use AIR's fibo only.