I have a web site built using ASP.NET 2.0 and Visual Studio 2005.  If also
have a C# assembly that was compiled using VS 2003, so this assembly runs
under the 1.1 framework.

If I use this assembly built for the 1.1 framework within my web app that
uses the 2.0 framework, is there any performance penalty incurred here?  In
other words, am I creating some sort of "cross boundary" communication that
has to occur between the 2.0 framework and 1.1 framework?  Or is there no
performance penalty and just a matter of the 1.1 code not having access to
specific features of the 2.0 framework.

The dilemma I have is that I have to redistribute to developers my C# class
library.  Some developers are building ASP.NET 2.0 apps, while others are
using 1.1.  I do NOT want to wind up creating separate installations, one
that has my 2.0 compiled assembly and another that has my 1.1 compiled
assembly.

I could do this within one installer package and dynamically determine the
.NET framework and install the appropriate version of my assembly
accordingly.  However even this approach has major problems.  Specifically,
I could easily see how someone would install on a ASP.NET 2.0 machine, and
then wind up transferring my assembly DLL to another machine that only had
the 1.1 framework which from what I understand would break things.  Or
likewise they may install on 1.1 and then transfer the DLL to a 2.0 machine
and never realize the assembly was really running under the 1.1 framework on
that machine despite their app using 2.0.

What is a developer to do?

Steve