The default value of TX_RXDETECT_PRECHARGE_TIME = 17'h155CC extends the receiver detection time by about 250 microseconds. While this might be acceptable in hardware, software simulation takes longer to simulate receiver detection.
When using ISE Design Suite 13.4 and receiver detection, TX_RXDETECT_PRECHARGE_TIME must be set to 17'h00001; this will reduce the time it takes to complete receiver detection to similar duration as the 7 Series FPGA GTX Transceiver. The PIPE wrapperfor PCI Express has been updated with this value. Customers not using the PIPE wrapper will have to update this setting manually.