I think mod_deflate may burn more CPU powers to run gzip compression. Thus, if mod_deflate has no cache strategy for compressed contents, then 'Apache CPU Load' graph must be increased as Apache Bytes / Apache Requests increases.
But cacti graph shows different result from my prediction. I adopted mod_deflate at about Tue 13:00, CPU Load went up sometimes, but it falls right after.
My Question is : does mod_deflate has its own cache strategy?