There are two patches (or actually a reimplementation of the xrx200 legacy driver) out there: How to make the lantiq xrx200 faster, which I have also tested but not benchmarked. Apart from that, I have only done one performance test and that was to check, if the box running two OpenWrt instances would for wifi clients be fast enough to fully use my 80MBit VDSL and it did. I have not checked the switch performance on the Lantiq SoC in any way.