Regarding the MAX_ALLOC_PERCENT environment variable:

This setting is CASE SENSITIVE! I got stuck on this for a while. Go to your Environment Variables Settings panel:
Click the Start Button
In the search box type "var" without quotes.
Choose the "Edit the system environmental variables" option.
Click on [Environment Variables...]


Verify that MAX_ALLOC_PERCENT is present in ALL CAPS with a value of 100.

This will allow you to increase the thread-concurrency.