Now that we're talking real money (via cloud credits) for WL execution time, are there any plans to eventually support CompilationTarget -> "C", for example? Even the trivial examples in the documentation show ~7x performance increase.
Speaking to the larger picture, especially for newcomers to WL, it's notoriously easy to write code that performs slowly - how will Wolfram help mitigate this with deployed code?
We definitely would like to see CompilationTarget -> "C" supported in the cloud down the road. The limiting factor there is that we currently block both child processes (for invoking the C compiler) and LibraryLink (for arbitrary user-generated LibraryFunctions). You can use Parallelization->True now to speed up certain types of Compile expressions.
CompilationTarget -> "C"
To your broader question, note that you can develop your code and measure its performance in a notebook prior to deploying it. Also, now that we have a product focused on programming that incentivizes efficient code, we'll have both better avenues for disseminating best practices and an interested audience for this topic.
Is LibraryLink also planned to be supported, along with CompilationTarget -> "C"?
I do not know the security implications, and I can imagine that this wouldn't be possible.