This is a simple script which will export information about your SharePoint 2013 environment into txt and csv files. download here: SPFarmReports For detailed report I would recommend using SPDOCKIT available for download from here: http://www.spdockit.com/
Microsoft’s Performance and capacity test results, recommendations and scenarios are now available for SharePoint 2013see: http://technet.microsoft.com/en-us/library/ff608068.aspx The papers cover SharePoint 2013 Performance Counters, benchmarks (Green and Red Zones) and expected throughputs. Luke
This blog contains information on how to performance test SharePoint 20102013, to benchmark the load the SharePoint farm is under.