Turn on compiler optimizations

Because reasons.

rebar.config

@@ -7,7 +7,7 @@
 ]}.
 
 {port_env, [
-    {".*", "CXXFLAGS", "$CXXFLAGS -g -Wall -Werror"},
+    {".*", "CXXFLAGS", "$CXXFLAGS -g -Wall -Werror -O3"},
 
     {"(linux|solaris|freebsd|netbsd|openbsd|dragonfly|darwin)",
         "LDFLAGS", "$LDFLAGS -lstdc++"},