DragSelectRecyclerView | TouchListener that can be | RecyclerView library

I am currently trying to achieve an app to edit weekly timeframes. Like mechanical timers for sockets, but in my case for every weekday.

The granularity is in the first place secondary (i guess it will be 15 or 30min).

My approach was a RecyclerView with GridLayoutManager and an ArrayAdapter with Items for every Cell.

To select more cells you can longpress a cell and drag over others. To achieve this I used the Listeners of the following Library DragSelectRecyclerView.

It works pretty well and you can select the items quite good but especially on the emulator or older phones its very slow and laggy. In the debug logcat you can see also that the Choreographer has to skip many frames at rendering the View and on selection of multiple cells.

Is there an better approach to achieve such an behavior. Or is there any big mistake in the code which is very slow and crappy?

EDIT:

after changing notifyItemChanged(pos); to notifyItemRangeChanged(pos, pos); its way less laggy but still not performing as well as it should.

I also removed everything that was responsible for autoscrolling (which was a feature of the library i mentioned above) to make the code simpler.

Here the source of my Fragment