Performance Tip - Build in Release

[tomblind]

Following up on thestr4ng3r/chiaki#374 here, since that's locked now.

I finally got around to trying to optimize chiaki for the Pi Zero again, and one of the big things I've found is embarrassingly obvious: I wasn't building in release, and thus wasn't compiling with optimizations on. This gave a pretty huge boost in performance (barely ever hitting 100% cpu now).

I recommend adding a tip about this to your wiki, for folks like me who aren't as familiar with cmake:

cmake .. -DCMAKE_BUILD_TYPE=Release