Checking a Cython extension for CPython interaction

When installing Finesse, during the build process of the Cython extensions, HTML files are generated for all .pyx files which show the level of interaction each line has with the Python Virtual Machine.

An example of this is shown below. The yellow lines indicate Python interaction with the opaqueness of the colour giving the level of this interaction - i.e. stronger yellow means more Python interaction. These lines can be expanded to show exactly which CPython functions are being called.

When inspecting these annotated HTML files you should look out for any yellow lines present in the bodies of loops. It is these lines which are likely to be the culprits of bottlenecks in the Cython extension performance.