You should compare apple to apple. S&P 500 is not "growth" fund. Is there another growth index fund that would match better? Maybe Nasdaq qqq index fund?
I don't agree. This isn't apples and oranges. Money is money. Grading investments over a time horizon is an equalizing assessment. Not every growth company is on the NASDAQ exchange.
Edit: I also disagree with the S&P500 not being a growth index. Any index comprised by the top x companies in any category that rebalances on a regular basis is a growth-oriented index.