There is not a specific Microsoft doc or article to explain this HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\BITS\Performance key and its sub keys.
You may check this technet case for some information:
How to use lodctr to resolve Event ID 1008 issue
============================================
If the Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.