Hey peeps,
I just wanted to share a really awesome tool I found to backtest your ETFs portfolio performance. It’s from a belgian startup curvo.eu who want to introduce the concept of savings (via index funds) to the masses. It’s a cool startup and is mainly geared towards European Investors (as the info on the web for european etfs is very small).
They haven’t launched their product yet but they provide this backtesting tool where you just have to pick your fav. ETFs and you can see how your protfolio could have fared so far and the best part, it can suggest you the optimal allocation for the funds you pick, the best rebalancing strategy etc… 
Give it a try 
Cheers