Visio 2003 addon/add-in VB.NET marshalling performance

[Philippe TEIRUH]

Hello,

The performance of my application dramatically decreased when I rewrote my
add-on into an add-in.

My add-on was written with VB 6.0 and VC++
My add-in is written with VB.NET

The following call to Visio (from my add-in) needs 3 milliseconds (far too
much!) to be executed:
objShape.Cells("Prop." & sCellName & ".Value").FormulaForce =
Chr(ASC_DBL_QUOTE) & sValue & Chr(ASC_DBL_QUOTE)

Is it a marshalling/thread compartment problem?
Can you explain me what to do to improve the access time to Visio code?

Thank you

Philippe