**Background**

We have an existing application which can load data into Microsoft Project so it can be manipulated by MS Project.

The original application is an old-style COM Project add-in written by VB6 targeting on MS Project 2003 / 2007, and now we are planning to migrate them to VSTO add-in targeting MS Project 2013 / 2016.

**Problem**

For them COM Add-in solution, we have encountered performance issue:

> 
> Testing project has 4414 activities (av\_activity table) and 8330
>  relationships (av\_reln table).
> 
> 
> Performance issues were reported during Load operation: 
> 
> 
> 
> > 
> > Load time on MSP 2003 template for above project is apprx: 30-35 mins. 
> > 
> > 
> > Load time on MSP 2007 & 2010 template is > 3hrs
> > 
> > 
> > 
> 
> 
> 

For VSTO solution it gets better but still we hope can improve the loading performance by some means.

**What We Have Tried So Far**

We have tried several tricks but didn't get much effect...

* Diable auto calculation during adding data

`_application.Calculation = PjCalculation.pjManual;`
* Disable screen updating during adding data 

`_application.ScreenUpdating = false;`
* Disable change highlighting

`_application.EnableChangeHighlighting = false;`
* Disable status bar

`_application.DisplayStatusBar = false;`
* Set the Undo value to 1
* Set default View to "Task Sheet View" (instead of "Gantt View" which incurs more overhead during load).

**Seeking Help For**

I am seeking help for any solution on improving performance while loading data into MS Project with VSTO Add-in and C#.

Thanks in advance!