The current software model for GTHE2 makes the simulation runtime slower compared to the GTXE2 software model, specifically on the RXCDRLOCK assertion after the transceiver is reset/initialized.
For ISE tool versions prior to 14.4, please use the following work-around to make the simulation run faster:
CFOK_CFG = 1'b1
Current recommended setting for GTH:
CFOK_CFG = 42'h248_0004_0E80 for hardware
In simulation, please change the setting of this attribute to speed up simulation:
CFOK_CFG = 42'h248_0004_0F80
This runtime issue is scheduled to be fixed in the ISE 14.4 design tools. After this is fixed in 14.4, the above work-around is no longer necessary.