ehci / ohci driver – Resume take a longer time from S3 in VISTA

Hi,
In VISTA, I have updated to SP1, disable USB selectived suspend and disable C3 state in duo core processor.
I use Pwrtest to test the USB EHCI /OHCI resume time form S3 after cold reboot,
but the EUCH resume time is always near 2000 ms.

If I idle the system or do something for a while, the ehci S3 resume time will reduce to 50 ms.
I trace the DPC of USBPort time in the fault resume test, the long resume time (250-500ms) will have higher frequency.

I got some descriptions from Microsoft hotfix website, it tells me “UHCI host don’t support sleep mode in VISTA.”
Is it a problem what I met ?

Thanks