[Plugin: W3 Total Cache] if page-cache, why DB-cache? GZIP?

What does DB cache do that page cache doesn’t do? I imagine page-cache storing the “entire page” on disk, so I am not quite sure what would be the use of caching anything from the DB in addition. Anyone would be able to explain the difference between these in layman’s terms? How can they co-exist to improve performance?

We have a mid-sized website, and I’m considering not using DB-cache or Object-cache because page-cache+minify seems to be making the bulk of difference. Is there anything I am missing out on? Sorry, I guess I just don’t really understand what these caching methods do …

W3TC caches differently layers of WordPress for different purposes. A page cache is going to give a user the HTML for a site faster than other caching methods. A database cache reduces the load on the database which reduces the time to generate a new page for a visitor when needed. Not all caching types and methods are necessary for every site. W3TC is a swiss army knife and you should try. In general caching object cache and database cache to disk is not recommended.

I find it weird, on the “General” page, there is “[ ] Deselect this option to disable all caching functionality”. This option is UNCHECKED by default, implying that caching is not enabled. However, when I check it and click save, it enables ALL caching methods, including CDN which I don’t want. When I then proceed to uncheck the caching methods I don’t want and click “save”, this checkbox once again reverts to unchecked fooling me to believe the caching is not enabled. Is this some inconsistency, or is it just me being stupid?
http://d.pr/FlBo

This is a bug ignore for now.

My tests show that cache for a specific page is automatically refreshed if the content(DB/textcontent) changes. I guess this makes sense from a functional perspective, but can anyone confirm this?

Yes, that is the intended behavior.

Does page cache refresh automatically at some interval? Or is this what “[ ] Automatically prime the page cache” settings are for? I can’t see anything else (like on the minify page) which controls how often page-cache is refreshed. Perhaps it is not required, especially if the page-cache is purged if the content is updated?

To avoid caching files that are no longer needed, they expire. Priming the cache attempts to keep more pages of the site cached and somewhat fresh.

page-cache+minify seems to handle the bulk of caching pretty well. I am really not sure about DB cache and Object cache. Should I perhaps just enable them and use with default settings? I been reading several posts and can’t seem to find any consensus, neither can I find any noticeable difference when testing

See above. It sounds like you have a shared hosting account.

Is http GZIP compression ONLY enabled for css/html/js if I activate browser cache? I am trying to understand the logic in that … This seems to have been moved from other sections in previous versions of W3TC –

Look more closely the option is available for various media types respectively.