>I just found something that I just can't find the reason. I have a terrible slowdown in one of my .NET application.
>
>If I have this:
>
>

>                        If cCurrentField = "No_Claim" Then
>                            lcHtml = lcHtml + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>"
>                        End If
>

>
>as part of a loop which is executed 200 times, it will take one second to execute the loop 200 times.
>
>But, if I have this:
>
>

>                        If cCurrentField = "No_Claim" Then
>                            lcHtml = lcHtml + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>" + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>" + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>" + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>" + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>" + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>" + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>" + "&ClaimNo=" + Trim(oRow("No_Claim")) + "&MitTelAI=" + _
>                             LTrim(Str(oRow("AI"))) + "&Hd=1>"
>                        End If
>

>
>as part of a loop which is executed 200 times, it will take 7 seconds to execute the loop 200 times.
>
>What is going on? Why is it that simply adding a longer string causes the process to crawl?

Michel,
(Not sure if this can be an exact explanation).
Strings in .Net are reference types and immutable. That's when you concatanate a string with another new string is not simply added to the end of the other in memory, but a totally new string is created.
Within each call you're effectively creating a series of new strings in memory + a new lcHtml string.
.Net StringBuilder class is for things like this. Use it. It effectively optimizes the process and is fast. Yey another alternative is to create a stream and append to that stream. ie:

Dim sb as new StringBuilder()
sb.Append(lcHTML)
                        If cCurrentField = "No_Claim" Then
for 1 to 8 
  sb.AppendFormat(  "&ClaimNo={0}&MitTelAI={1}&Hd=1>", _
              Trim(oRow("No_Claim")), _
              LTrim(Str(oRow("AI")))   )
next
                        End If

or: If you prefer:
sb.Append("&ClaimNo=")
sb.Append(Trim(oRow("No_Claim")))
sb.Append("&MitTelAI=")
...
series.

Cetin