The custom scrolling feature takes over the default scrolling logic in order to ensure that grid scrolling works without a lag on devices. To enable, you must include the 'ui.grid.customScrolling' module and you must include the ui-grid-custom-scrolling directive on your grid element.
This plugin is exactly what I've been looking for (for several months!) to solve ui-grid top and row select header scroll lag on mobile devices. While it does seem to force the grid data to synchronize with the headers, it significantly lags the data X/Y scroll in the process. Because of this, I am forced to leave the grid in its current state so at least the data scroll is responsive. Please let me know if there's anything I can do to improve the data scrolling performance on mobile devices.
I have tested it on our production handset, a Honeywell CT50, as well as my own mobile phone, a Nexus 5X (both running Android). Additionally, I have used the grid in both the browser and native application on both of these devices.