Valid point. I could show a comparison to known funds or stocks to give an idea of the real performance

Great idea, will add

It does not use a single risk free rate for all excess return calculations, but rather matches each return with the risk free rate of the day.

One of the benefits is that the risk free rate is kept up to date on a daily basis. The calculation matches for each day the actual risk free rate, rather than just using the latest available value.

Right now it uses the total stddev of the portfolio, over the full history provided. It can be changed fairly easily to compute it over a moving window of 1/3/5 years.

Good point, will add something to give a bit of guidance.