I am writing a script to tokenize file contents. I've written a tokenizer in JavaScript, but it gets pretty slow with large files (5+ seconds). Since I'm retrieving the files from the server anyways, I am considering rewriting it in PHP to shave off a few seconds. I've read that the speed difference between PHP and JavaScript is negligible, but if the files are 1mb or bigger, a small speed difference could add up. I found this benchmark online, but I'm not sure if the info is up-to-date (with all the JS engine optimizations from the past couple years).
Porting over all my code would take some work, so if I can help it, I won't use PHP. But if its going to be much faster (25-30%), it would be worth it.