How to draw millions of points on google maps?
I believe the answer is don't. That's too many markers. Per the table below (grabbed from geek.com) you would have a screen with nothing but markers and no map, even if each marker were only 1 pixel each, which they aren't.
There are ready solutions for marker clustering like Markerclusterer or Markerclustererplus.
You can find these libraries on github:
https://github.com/googlemaps/v3-utility-library/tree/master/markerclusterer
https://github.com/googlemaps/v3-utility-library/tree/master/markerclustererplus
Sample pages and documentation are inside these repositories. Could it work for you?