[dataflow]

I think the core of the optimization you're mentioning hinges on a normal lookup being a slow hashtable lookup (of a string?)... whereas I imagined the first thing the interpreter would do would be to intern each name and assign it a unique ID (as soon as during parsing, say) and use that thereafter whenever they're not forced to use a string (like with globals()). That integer could literally be a global integer index into a table of interned strings, so you could either avoid hashing entirely (if the table isn't too big) or reduce it to hashing an int, both of which are much faster than hashing a string. Do they not do that already? Any idea why? I feel like that's the real optimization you'd need if checking a key in a hashtable is the slow part (and it's independent of whether the value is being modified).