The only problem with pdf-Xchange is that moving around in the doc feels sluggish; you can see pages redrawing
-urlwolf
I have this problem with Adobe Acrobat Reader (7 through 9) as well, with 2D acceleartion enabled. Happens with larger, searchable pdf files that I have generated (or modified) from image files. For example, I get a pdf that I can't copy selected text to the clipboard from and use PDF Converter Professional 5 to convert it to a searchable pdf. Often, I can watch each individual page redraw as I scroll through it. Very annoying.
Regarding resource usage and performance, have you tried using one of the Acrobat speedup applications such as
Adobe Reader Speedup? I used to run Fox-It Reader because of the drag on resources from Acrobat Reader, but discovered Adobe Reader Speedup and have never looked back...