While there isn't yet any feature that allows you to run a sales performance -by employee report more straightforwardly, you could use a workaround by exporting the data to an excel spreadsheet, and it would only take a few steps:
1- From Sales Order, on the top right, click the excel icon to export the data to a spreadsheet.
2- Ensure to check out "sold by.", on the popup window.
3-Finally, on the excel spreadsheet, add filters on the Data tab, in the Sort and Filter group. This way you can keep track and trace of your sales