The stdout output is frequently *very large* (it can be megabytes in some cases). It is currently sent with the following headers;
 * cache-control:no-cache, must-revalidate
 * date:Tue, 22 Nov 2016 05:22:28 GMT
 * expires:Fri, 01 Jan 1990 00:00:00 GMT
 * pragma:no-cache

Which forces the browser to fetch it every time. 

Once it the task has complete, this output should *never* change. Hence it is very cacheable.

One solution to this is using ETags. By providing an ETag which is a hash of the content we can get caching behaviour (but the browser still needs to check each time).
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> The ETag field here refers to some state identifier for the returned 
> document. Later, a browser can specify that same identifier via If-
> None-Match and the server can decide to say that the document has not 
> changed instead of sending the document again.
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