To get a random element from an array faster, use the following instead:
# Make sure to call `randomize()` once (and only once) in a script's `_ready()` function first.
# Don't call `randomize()` multiple times as it will slow things down.
return rand_list[randi() % rand_list.size()]
This is because you don't need to shuffle the whole array to get a single random element from it.
If you need to do this a lot, consider inlining this function where you need it instead of creating a dedicated function, as function calls are relatively slow in GDScript (and cannot be inlined by the compiler as of writing).