A few quick tests to see how much speed you lose by evaluating pre-parsed statements, rather than generating a function with new Function(...) to do it for you. Follows this discussion.
Open a new tab to about:blank, open the console, copy and paste test.js. The results I get:
inline statement: 1.847ms
normal function: 1.852ms
generated function: 1.707ms
naive evaluation: 35.201ms
primed evaluation: 8.932msInterestingly, a generated function is just as fast as an inline statement. (I tried including eval in this test, but it’s so shockingly slow that I had to close the tab. We’re talking 2-3 orders of magnitude slower.) Evaluating code yourself is ~4.5x slower - given that we’re still talking about >100m/sec for the example at hand, it’s unlikely to be a bottleneck in any real-world apps, but we certainly don’t gain any performance (though we do gain CSP compliance and the ability to thwart certain attacks).