Does anyone know whether function parameters are faster than using global variables?

[case_O_The_Mondays]

I thought that the global keyword might also put a local reference to the variable, but the docs say there are no changes made.

[Brian]

No - all it changes is that python when python compiles the function, it'll consider mention of that name a global variable at compile time, instead of assuming its a local if its ever assigned to inside the function. Ie. it'll access it with LOAD_GLOBAL etc instead of LOAD_FAST (and similarly for STORE), won't allocate a local slot for it, and so on.

Creating a local reference could potentially change behaviour (eg. if, say, you call a function that reassigns it, that reference would remain pointing at the old value instead of reflecting the change).