Better Photoshop display

http://www.extremetech.com/article2/0,1697,1910617,00.asp you can fix this by increasing your number of image cache levels in the preferences. You can specify the number of cache levels in the Preferences>Image & Memory Cache screen (Figure 4). Needless to say, the higher the number of cache levels, the more resources Photoshop needs to consume. If you have limited RAM, or scratch disk space, you may wish to set the level to 1 or 2; the default is 4 levels. You can go as high as 8 levels, which will give you cached views at 66.67, 50, 33.33, 25, 16.67, 12.5, 8.33, and 6.25%. Setting the cache level to 1 is the same as turning it off because only the current view is cached at that setting. But I tried it, and I didn't see any difference at all.

gentle is correct, it's all about the even multiples. This is all about speed, it would be scandalously slow otherwise.

If PShop used the GPU to do screen scaling, I don't think it would be scandalously slow.

Zooming in, you probably don't want bicubic interpolation, you want big blocky pixels that you can tweak individually. Zooming out, you probably don't want bicubic interpolation, you want some kind of averaging. If I'm viewing at 10%, bicubic interpolation means only 16% of the pixels (4x4 out of 10x10) contribute to the output! Still will look ugly. Correctly downscaling a large image can be fairly slow, but I think the real reason they don't do it live is not the downsampling part of it, but the fact that that would require the full image to be rendered each time it is drawn! As it does it now, it only has to render the number of pixels visible in the window, no matter how big your image is. Given that Photoshop is largely inteneded for print-use, actual images will often be MUCH MUCH larger than your screen. Switch back and forth between 25% and 50% I guess is my only advice to you.

A GPU can't operate on images that large.

I had the same frustration when I first encountered Photoshop. Now I just work at 12.5, 25 or 50, using keyboard shortcuts to get around. Ctrl (Command) and = zooms in, Ctrl (Command) and - zooms out, and Ctrl (Command) and 0 zooms to such a level as to fit the entire image on screen. Spacebar turns the cursor to a Hand tool for dragging your way around. Now things may be very different for you (and you may know all this already - if so, sorry), but I find myself saving a lot of time using Ctrl+0 to see the whole picture, hitting z to set the tool to the Magnifying Glass, and quickly dragging a box round the area I want to see. Often, I'll then Ctrl + =/- to get to a crisp zoom percentage.

"A GPU can't operate on images that large" That's arguable. Apple's Aperture, uses the GPU pixelshader units to accelerate the processing of raw sensor data from digicams, including the 16.7 Mpixel images from a Canon EOS 1d. 6XXX series Nvidia CPUs can support 4k by 4k texture sizes. ATI looks like they may still be at 2k by 2k, but I'm not convinced that multiple textures couldn't be tiled.

The best way to deal with this is to zoom to the view you want and then shrink or enlarge it using cmd+ and cmd- (apple) or ctrl + and ctrl - (windows). This will 'snap' the view to the nearest multiple-of-two view which will look nice. I use this every time I zoom. And, yes, it sucks. I am hopeful this is one of the things they will fix in CS3 (along with the deplorable display of images in Bridge, which I'm told by an Adobe insider is due to caching the images as low-quality jpegs).

You'll stop noticing this after using Photoshop for ten years or so.