Windows Server 2008 R2 STD doesn't accept first attempt to RDP

Finally, I've been able to resolve this after a couple of days.

This is what have been done to fix it:

Step I:

Added a new DWORD key named DisableTaskOffload with a value of 1 to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

Step II:

Changed IPv4 Checksum Offload for PROD NIC in Advanced Settings.

After these changes, no more issues with RDP not been connected at first attempt or performance issues.