Update: the patch is now live on Steam. It adds the options noted below, CPU and SLI optimizations, implements a workaround for the intro crash for AMD users, and more. We'll update the tweak guide with the pertinent info Tuesday; in the meantime, head here for extensive notes.
RAGE isn't the worst PC port we've seen, but it's certainly not the best either, as noted in our review. Much of the issues stem from a lack of graphics options, the "intense" reaction to which technical director John Carmack says he was "surprised" by.
Fortunately, at least three are coming "soon" in an update (more are being evaluated), on top of some new default settings which should play better with various CPU and GPU combinations, and likely some tweak parameters, of which we already have many in our tweak guide. Here are the three options already implemented:
1. Texture Cache [ Small | Large ] which alternates between 4k and 8k pages
2. Texture Anisotropy [ Low | High ]
3. VSYNC [ Off | On | Smart ] "Smart" will only be available once future drivers come out that supports the extension so Off and On are the only options when the patch initially hits.
Bethesda has noted an editor and 64-bit .exe are coming at some point as well.