Fixed fast scroll performance

app/src/main/java/androidx/recyclerview/widget/FastScrollerEx.java

@@ -449,12 +449,14 @@ public class FastScrollerEx extends RecyclerView.ItemDecoration implements Recyc
         if (Math.abs(mVerticalThumbCenterY - y) < 2) {
             return;
         }
-        int scrollingBy = scrollTo(mVerticalDragY, y, scrollbarRange,
+
-                mRecyclerView.computeVerticalScrollRange(),
+        int scrollbarLength = scrollbarRange[1] - scrollbarRange[0];
-                mRecyclerView.computeVerticalScrollOffset(), mRecyclerViewHeight);
+        float percentage = (scrollbarLength == 0 ? 0 : y / (float) scrollbarLength);
-        if (scrollingBy != 0) {
+        androidx.recyclerview.widget.RecyclerView.Adapter adapter = mRecyclerView.getAdapter();
-            mRecyclerView.scrollBy(0, scrollingBy);
+        int count = (adapter == null ? 0 : adapter.getItemCount());
-        }
+        int pos = Math.round(count * percentage);
+        mRecyclerView.scrollToPosition(pos);
+
         mVerticalDragY = y;
     }