foto-z- they just changed that! I mean brush size in liquify was much lower before.Fact is Liquify takes a lot of power to preview, and this limitation is to stop people on slower machines causing what looks like never ending freezes while using the tool.
There is quite an old workaround to this, which I'll go though in detail
• duplicate your Liquify layer into a new file (right click on it in the layers panel and while holding option choose duplicate layer). After choosing New in the drop down, this will straight away put the layer into a new document.
• Downsample this new file to 25% of its original size- Image Size/ Percent - 25%
• Go into liquify - do your liquify on this downsampled version - much quicker to operate and to preview
• Before exiting Liquify Click "Save Mesh"
• Go back to the original document and then open Liquify on your original Full size layer
• Load the liquify mesh you just saved down. Commit it
Some of these steps can be ACTIONED - meaning that most of the process can be automated. It will allow you to do your work on a much lower res file, and perform a high quality distortion on the high res.
Now a good Freature request would be Make Liquify work using Open GL - this would make the tool less clunky and slow, and allow better zooming and navigation
Thanks for the workaround! There is actually a modified version of the Liquify filter available on the net which gives you a 9000 pixel brush and works on CS4. However, that is not as good as a native fix, of course. If Adobe is worried about performance on slower machines, they could pop up a warning notice. That has to be better than blocking the feature from all users!