Will it be any performance issues when referencing 2.0/3.5 assemblies from .net 4.0 project?

I've found a lot information in internet about this, but I can't ans开发者_开发技巧wer for myself; will .net 4.0 application work slower if I add .net 3.5/2.0 assembly, and should I recompile them in 4.0 if I can?

I don't think you should worry about performance in this scenario. The 2.0/3.5 assemblies may actually work faster, since there is potentially less code overhead (in some rare cases).

But that's all micro-optimization anyway, and the only way you're going to know for sure is to profile your code, and see how fast it really is. I think you're going to find in the vast majority of cases that it isn't going to matter.