Is there any difference between "Platform 32-bit" or "Platform 64-bit" for Azure Functions?
I would not suggest switching the Functions worker process to 64 bit. It will not run any better, and the memory usage will end up being higher (as it always is for 64 bit). Also, at this point Functions has only been tested in 32 bit mode so you may run into some unexpected issues in 64 bit.
Update (2/6/2017): see this question for latest, as well as https://github.com/projectkudu/AzureFunctionsPortal/issues/894.