too bad i have to revert to ditto.
I've been using Ditto for a long time now(*), but I have never seen it take any significant CPU time (on XP). When idle, it doesn't even register in Process Explorer. The same when showing the window and scrolling through contents. Checking right now, I am only seeing a spike to 6% CPU when copying text to clipboard, for a split second, but this of course is negligible - and I'm running winamp now and some other working processes, so the actual Ditto usage is probably 3% or so.
I have it configured to keep one thousand most recent clips, for up to 7 days, with duplicates eliminated (searching for dupes may account for the momentary spike on copy), and I keep only text clips. I'm mentioning this on the remote chance that the way Ditto is configured on your system requires it to do a significant amount of housekeeping.(*)
I've tried almost everything else, and Ditto it's the only clipboard manager interface that really speeds up my work a lot. Perfect keyboard-only access, superfast filtering on typed substrings (more than just incremental search), and it positions itself next to text caret, so it always shows up at the spot your eyes are focused on. Unicode helps too, since I often deal with more than one language. I just turn off the networking support, and wish someone would recompile Ditto without it altogether.