Its pretty simple but maybe the performance fee name is a bit confusing.
The pool has the following structure of interest payments:
- 80% of interest goes to lenders
- 10% goes to pool cover providers
- 10% goes to the pool delegate
On top of that, borrower pays an extra 1% annualized establishment fee, 2/3 of that goes to Maple treasury to buyback MPL tokens on the open market and distribute to xMPL stakers. 1/3 of that goes to the PD.
When the webapp displays 5% loan to Wintermute = Wintermute pays 5% + 1% establishment fee.
Lenders receive 80% of 5% per annum = 4% net yield in wETH on that particular loan.
Hope that clarifies your question 