PixivBridge caching, how does it work?

[kattjevfel]

The docs state:

As Pixiv requires images to be loaded with the Referer "https://www.pixiv.net/" header set, caching or image proxy is required to use this bridge.

and then only goes on how to disable caching, but I can't seem to get caching to be turned on.
I am assuming having it on would make images be cached on the server instead of linking directly to pixiv, but perhaps this is incorrect?

I have cache type set to sqlite and the timeout seems to make absolutely no difference.

I currently have to use an image proxy but it is very slow and I'd rather not have to do that.