In the s() function there is a comment saying that certain changes should be made to the function parameters to make it faster once Moodle requires PHP 5.4.

Since Moodle does in fact require PHP 5.4 I suggest we make the changes and remove the comment. I've checked and it seems like these changes will result in a very small performance improvement; on a typical course page where there are 8,000 calls to s(), it will probably save about 2ms. So not measurable in normal use but hey we make the code shorter by removing that commment...

There is a fairly decent unit test covering s(), which still passes after this change.