Cargo.toml: flip real optimizations on

Since I don't expect to pull in any more significant dependency, and we
are far from running out of the 1MB compressed limitation of code size,
we should be perfectly fine flipping this on instead of sticking with
optimizing for size

Cargo.toml

@@ -61,6 +61,5 @@ wee_alloc = { version = "0.4.2", optional = true }
 wasm-bindgen-test = "0.2"
 
 [profile.release]
-# Tell `rustc` to optimize for small code size.
-opt-level = "s"
+opt-level = 3
 lto = true