steps to reproduce

1. run the attached project (version 3.8.3.FL.20160106-Eval)
2. test under Firefox 42
3. in merge(), call notifyAffectedRange(event);
4. click headers to insert columns upon the order below
   9103
   9131
   9119
   9160
   9150
   9170
   9105
   9110
   
5. in merge() , change to call notifyLoadedRange();, perform the previous step

result

• see attached report
• notifyLoadedRange(); is slower than another approach.
  Execution time: measured from clicking the header cell to seeing a rendering complete.
  

• But the number of cells in this range is smaller (225120) than another (325242). The loaded range doesn't reduce during scrolling, it starts from A1:DE201 to A1:FO201 during testing
  
• notifyLoadedRange(); have average bigger response size than another.
  

expected result

• notifyLoadedRange(); is faster than notifyAffectedRange(event);
• The time taken by notifyLoadedRange(); doesn't increase by more and more column insertions.