DynamicExpressions | dynamic expression builder that can be | Database library

The problem is your GetPropertyGetter method generates a lambda that converts the result of the property into an object. When OrderBy sorts by object instead of by string, the comparison used is different. If you change the lambda to p => (object)p.Title you will discover it is faster as well. If you change the OrderByDescending to take a StringComparer.InvariantCulture, you will see a slight speed up over your generated lambdas.

Of course, that also means your dynamic OrderBy most likely doesn't handle other languages properly.

Unfortunately once you start to dynamically create code like the lambda for a LINQ method, you can't always just substitute object and expect the same results (e.g. an int field will be boxed, string won't use the same comparer, types with custom comparers may not work, ...). Basically I think of Expression building for dynamic type handling as like the GPL - it spreads out (and up) like a virus. If you replaced OrderByDescending(GetPropertyGetter) with dynamic OrderByPropertyNameDescending(string) and built the call to OrderBy as well, you would get what you expect.

Consider: