I confirm 1-3 secs. should be the time, approximately, for the system to wake up from Sleep mode. If it's taking much longer than that, then, I'd the following:
1. Ensure there's no conflict in Device Manager.
2. Just to be 100% sure, restart the system into BIOS by pressing <F2> during the boot process. Once in the BIOS setup utility, press <F9> to restore BIOS default settings. Reset any customized BIOS settings. Clear all DMI event logs by setting the option to "Enable", which is located in the Advanced/Event Log
Configuration section of the BIOS Setup utility. Press <F10> to save the new settings and reboot the system.
3. If the situation still continues, I'd recommend checking with the Operating System developer.
Well finally it was a TFT issue, such TFT BenQ BL2400PT has a Eco-mode that when the user is off place it shuts down (turning it off and everything's back to normal), but such Eco-mode its not working well, so it turns TFT off even if user is working with the PC.