Board Thread:Geometry Dash Gameplay Discussion/@comment-26125348-20160123080513/@comment-33322458-20180505192909

Found this information here.

-1x Speed: 8.4 blocks per second

1x Speed: 11.2 blocks per second

2x Speed: 14.0 blocks per second

3x Speed: 16.8 blocks per second

4x Speed: 19.6 blocks per second*


 * Calculated this myself