<p>I want to create a simple http proxy server that does some very basic processing on the http headers (i.e. if header x == y, do z).  The server may need to support hundreds of users.  I can write the server in C# (pretty easy) or c++ (much harder).  However, would a C# version have as good of performance as a C++ version?  If not, would the difference in performance be big enough that it would not make sense to write it in C#?</p>

The proxy server you describe would deal mostly with string data and I think its reasonable to implement in C#.  In your example,
```
```
if header x == y, do z
```
```
the slowest part might actually be doing whatever 'z' is and you'll have to do that work regardless of the language.