Limiting the maximum size of a resource to optimize

Restricting and Controlling PageSpeed optimization rewriting

A resource with large content takes a long time and a large amount of memory to process. You can specify the maximum length (in bytes) of the content for PageSpeed to optimize. The default setting is -1, which means content of all lengths will be optimized.

pagespeed MaxCacheableContentLength -1

This directive can be used at the server level.