OK so you're sure you have USB 3 ports and USB 3 devices right? [If you're not 100% sure click here]
So let's try and confirm that you actually have the Bluetooth+USB3 problem by trying to recreate it! There are two simple ways to check if you have the problem.
Test 1 : Try to replicate the problem and observe degraded performance to your Bluetooth device/s
Unplug all USB 3 devices from their USB 3 ports
Step 1 : Unplug all USB 3 devices from their USB 3 ports - If you have any uncertainty about what USB revision a USB device is then remove it.
Remember to check all sides of your computer for USB ports. If you are using a desktop computer there may be some additional ports hidden around the back of the unit so be sure to check.
Connect (pair) any Bluetooth devices you have with your computer
Step 2 : Connect (pair) any Bluetooth devices you have with your computer. If necessary pair each device again.
After connecting each Bluetooth device use it for some seconds to ensure normal functionality.
One at a time plugin any USB 3 devices into empty USB 3 ports
Step 3 : Now one at a time, plug any USB 3 devices into free USB 3 ports on your computer. Plug them in one at a time and carefully test that all your Bluetooth devices are functioning normally for at least a few minutes before plugging in the next USB 3 device.
If your Bluetooth device is a mouse make sure you move it around the screen for a minute to check if the pointer on screen starts to suddenly jump around (a common symptom for wireless mice with bad reception).
If you have a Bluetooth speaker make sure you start streaming music to it from the computer. If you have more than one Bluetooth device ideally try and use them all simultaneously. For example, play music and use your keyboard or mouse at the same time.
Did it work?
Hopefully you will find that upon inserting one of your USB 3 devices back into the computer that the performance of the Bluetooth device/s suddenly degrades. Removal of the same USB 3 device should return the Bluetooth device/s back to normal functionality.