In my haste to switch to using RazorEngine, I accidently the whole API. This has now been fixed.
Caching has been added to the Razor templates as well, based on [template-domain]-[template-name] keys.
Timings with ScrobblingApp are down to less than 2 seconds to read a database (must look into this) and saving a new instance and item in 50 milliseconds total. Not quite sure why those are taking so long.
Also, I've added API calls to the list of things that are excluded from having a session saved in the master cache, although it will be created and added to the context for the duration of the request.
By setting RazorEngine to emit raw strings instead of html encoding, this has increased the performance of the database read api call - the compiled, cached version is much faster at processing. Time is now down to 0.5 seconds to read the database of 10 items. Still needs massive improvement but it's a start.