1. A computer-implemented method comprising: storing a fetched resource in a web browser cache; determining at least one characteristic of the stored fetched resource; assigning, with a processor, a persistence score to the stored fetched resource based at least in part on the determined at least one characteristic of the stored fetched resource; creating a post-processed version of the stored fetched resource responsive to determining that a load time associated with the stored fetched resource exceeds a predetermined amount of time; storing the post-processed version of the stored fetched resource in the web browser cache in association with the stored fetched resource when the post-processed version is created; removing the stored fetched resource from the web browser cache based on the persistence score assigned to the stored fetched resource; fetching, in response to determining that a web browser requested the removed resource, the post-processed version of the removed resource from the web browser cache when the post-processed version is stored, otherwise re-fetching, from a server, the resource; and presenting, by the web browser, the post-processed version of the removed resource when the post-processed version is fetched, otherwise presenting, by the web browser the re-fetched resource.