Tail-calling

This language has functions that will have to be tail-called due to
having the ability to 'pause' its callstack, but some functions will
not and I was just planning to call them like normal functions. I am
wondering, would it be 'faster' (at execution of the compiled code) to
just put everything in the tail-call way, or is it still faster to
call functions like normal when I can?

When tail call optimization is enabled functions with the calling
convention fast (fastcc) follow a callee pops arguments convention.
This means that every function call (to a fastcc function) will be
followed by a sub [n callee pops slots] instruction.

Also functions that are tail calling must ensure that they don't
overwrite their arguments so there might be additional moves of
arguments before a tail call.