What is better: caching through HttpContext.Current.Cache or just a static?

Question

Last night I wrote up my first IHttpModule to do some request processing. I'm using a regular expression to inspect the raw url. The IHttpModule will be called on every request, so it seems reasonable to do some sort of caching of the regular expression object to prevent creation of it on every request.

Now my question... what is better: use the HttpContext.Current.Cache to store the instantiated object or to use a private static Regex in my module?

I'm looking forward to the reasons why. Just to clarify: the regex will never change and thus always be the same thing.

Answer 1

If the regex isn't going to change (and it usually isn't), then:

private static readonly Regex pattern = new Regex("...", RegexOptions.Compiled);

is the fastest and most efficient in every way

Answer 2

I guess it depends. Built in cache can offer you automatic expiration control while static objects can't. Also, if you want to change the cache mechanism (let's say you have to distribute your applicaiton) you can with built in cache. Static objects are just it, static.