This fork enhances performace for collection views with a lot of rows and fixed row heights. Only visible row frames get recalculated instead of all frames.
If the datasource changes or the amount of sticky rows/columns, you have to call
gridLayout.resetLayout()
Sticky Grid Collection View: Implementing From Scratch. See blog post for more details: http://www.vadimbulavin.com/sticky-grid-collection-view/