Not entirely orthogonal. Orkut's original C#/ASP.NET/SQL Server stack was an awkward fit for Google's predominantly Linux-based infrastructure, which made scaling and operating it more difficult. Almost all of Google's other web services were written in tight, optimized C++. David Jeske, Orkut's former technical architect, described problems with the .NET runtime, difficulties integrating with Google's infrastructure, and an eventual migration to Java and C++.
That doesn't mean C#'s execution speed was the primary bottleneck. In fact, Jeske's team reportedly made dramatic performance improvements while retaining .NET. But arguing that the choice of technology had no relationship to Orkut's scalability problems is just as misleading as blaming everything on C#.
The statement just mentions C#. Java is amazing and fast in capable hands, but so is C#. Of course you can have problems with a stack, but that's nothing to do with the stack in this case, but rather a skill problem associated with that stack.
If my current employer started having new software written in C instead of Java today, and while C has many problems, the problems we'd have would be all self-inflicted skill issues, not a direct problem with C.
These are orthogonal facts presented as if they were related.