Yup. BumbleBee Wiki is very helpful. Do NOT download and install nVidia like you are trying!
I followed those instructions setting up my new laptop with Nvidia Optimus and never ran into an issue with anything ever wanting a nouveau driver. At any point in your installation do you install nouvea? You never need to do that as far as I know. Sorry I can't be more helpful.
Honestly, glxgears is not a true benchmark. But the discrepency is suprising. Have you went through the Wiki (https://wiki.archlinux.org/index.php/Bumblebee) and checked if there is any troubleshooting steps? Also, how are you executing glxgears to test your results?