Symphony.

Trying to minimize the size on my server from a site with a lot of pictures, pulled from flickr: When pulling externally hosted pictures from feeds, these are by default not cached. However when you want to manipulate them in symphony, using the image function, they are cached (wether with or without expiry set). Is it possible to use the image manipulation without caching? Would the crunching of each picture upon load be an acceptable server load? or should I try to get by with the sizes flickr offers?

Also the external datasources themselves are also cached by default (though not huge in size I assume), where do these files reside? In manifest/cache? (nothing there with me)

It depends on your priorities but I'd generally opt for performance over storage capacity. Web space is cheap, so I focus on the optimal performance for my users.

If you disable caching of the external images, your page will load significantly slower than before. The reason for this is that rather than simply serving the image to the client, the server needs to make a request to Flickr for the image, download that image data, manipulate it, then send it to the client. This is an extra step that can have a noticable performance impact.

Depending on how popular your site is, and the extent of image manipulation you are doing, it's tricky to comment. But yes, it would undoubtedly add load to your server. If the images from Flickr are large (you're grabbing the Large or Original size) and thumbnailing them, then it will be slower than if you're grabbing the Thumbnail or Small size.

Wherever possible I load directly from Flickr. It takes the load off my server, and means Flickr serves the image without running it through a PHP script first. If you need to thumbnail, then I'd definitely recommend keeping caching enabled.

Alternatively you could choose the nearest Flickr size to match your design and crop using CSS using various techniques:

• Set as a background image on an element and fix the element's dimensions
• Load image inside a container that has dimensions fixed and overflow: hidden applied
• Use the clip property specifying co-ordinates (the neatest solution of the three)

I think the Dynamic DS XML is cached eithr in manifest/cache or manifest/tmp.