User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.0.249.78 Safari/532.5 Build Identifier: Add crypto hash functions for use by web pages, like SHA256. Computing these things in JS is not so fast... Reproducible: Always

JS is pretty fast these days, and on crypto-like code with integer computation SpiderMonkey tends to do very well. I wouldn't be so sure JS is unbearably slow without actually testing and seeing fundamental slowness. In any case, however, this isn't a JS bug but rather a DOM bug.

Thanks for moving to the DOM category. When doing AES/HMAC, SHA1 is the slowest part.