Invokes trace action for actions that are not traced

[breyed]

ITraceWriter is designed to not incur a performance cost for categories and levels where tracing is disabled. Specifically, traceAction should only be called if tracing is enabled. Accordingly, NlogTraceWriter.Trace should first check whether NLog is tracing at a given level, and only call traceAction if it is. This would provide a major performance improvement.

[panesofglass]

That's a great idea! Would you mind submitting a PR?

[breyed]

I wouldn't mind, but I'd rather not allocate the time to jump into this this project. It seems an easy fix. If not, I can help out.

On a separate perf topic, you could replace the lazy dictionary with a simple array and get a nice boost as well. In general, tracing libraries tend to be performance sensitive, so they are worthy of more optimization effort than other code.

[panesofglass]

@breyed, thanks for logging the issue.