Mention benchmarks in README

README.md

@@ -140,8 +140,11 @@ pwbox(message, password, {
 The default values for `opslimit` and `memlimit` are also taken from libsodium
 (`524288` and `16777216`, respectively). With the default parameters, `pwbox`
 uses 16 MB of RAM and completes
-with a comfortable 100ms delay in Node, several hundred ms in browsers
+with a comfortable 100 ms delay in Node and in browsers
 on desktops/laptops, and under a second on smartphones.
+(The package contains [a benchmarking script for Node](examples/bench.js)
+and [the page for browser benchmarking](examples/bench.html), so you can measure
+**pwbox** performance yourself.)
 You may use increased parameter values for better security;
 see the [crypto spec](doc/cryptography.md#parameter-validation) for more details.