Need advice on speeding up tableViewCell photo loading performance

Posted by ambertch on Stack Overflow See other posts from Stack Overflow or by ambertch
Published on 2010-04-29T06:24:49Z Indexed on 2010/04/29 6:27 UTC
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iphone

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uitableview

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uitableviewcell

I have around 20 tableview cells that each contain a number (2-5) thumbnail sized pictures (they are VERY small Facebook profile pictures, ex. http://profile.ak.fbcdn.net/hprofile-ak-sf2p/hs254.snc3/23133_201668_2989_q.jpg). Each picture is an UIImageView added to the cell's contentview.

Scrolling performance is poor, and measuring the draw time I've found the UIImage rendering is the bottleneck.

I've researched/thought of some solutions but as I am new to iphone development I am not sure which strategy to pursue:

preload all the images and retrieve them from disk instead of URL when drawing cells (I'm not sure if cell drawing will still be slow, so I want to hold off on the time investment here)
Have the cells display a placeholder image from disk, while the picture is asynchronously loaded (this seems to be the best solution, but I'm currently not sure exactly how to do best do this)
There's the fast drawing recommendation from Tweetie, but I don't know that will have much affect if it turns out my overhead is in network loading (http://blog.atebits.com/2008/12/fast-scrolling-in-tweetie-with-uitableview/)

Thoughts/implementation advice? Thanks!

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