So you're using it correctly. If you simply disconnect the enclosure's power supply unit, does the performance change? Or, the same? What I'm thinking is that either the enclosure's power circuits or the "wall wart" unit may be defective and failing to provide the power needed.
BUT before gong much further, check this. I see that you can detect the enclosure somehow on your laptop, but not all is well. Any brand new and empty HDD requires preparation for an OS to use it. The process is a two-step thing called Partitioning and Formatting, but modern versions of Windows combine this into a simple single step called Create a New Simple Volume. Until that is done, Windows' common tools like Explorer can NOT "see" the HDD and will not show it.
The way to do this preparation work in Windows is to use its Disk Management utility to find the new storage device, then RIGHT-click on it to Create a New Simple Volume. If you have not done this already, look in Disk Management for the drive in the enclosure. IF it shows there but does not have a Partition and Drive with a letter name assigned, then that is why Windows can't recognize it in Explorer. Do the Create.... thing, then back out of Disk Management and reboot to be sure Windows knows how to use the drive.
There's also another thing to check. In your laptop, have you installed the Device Driver for this particular USB3 device (the enclosure). It should have come with the enclosure on a disk, or you should have a reference to a website for downloading it. Check in your laptop's Device Manager to verify there IS a driver installed for it. Without a driver the laptop may not know how to communicate with it properly. If there is no device driver at all, then you may need to install that before doing the Create .... thing.