Why the concern?
Hard drives are cheap these days. Storage is plentiful. Aside from the 1TB SSD I'm running the OS on, I've got 11TB online. If you want to keep the primary storage device running lean, you could add a setting for locating your Recycle Bin (which I assume is different than the Windows Recycle Bin?) somewhere else, like on another drive.
Scanning the CH+S data folders, I note that it's keeping a copy of all copied images in the Files\[year] folders, so there's a lot of space in use that I had never realized before. Just an observation; I don't care that it's doing that. It could be a space consideration for some, though.
Don't know what db you're using, but a good indexing scheme should keep performance up.
You already have a setting to "Move from Clipboard Old to Recycle Bin after every X number of days" with a default of 90. That should keep the main clips running snappy whether you retain source formatting for all clips or not. Plus it puts the responsibility for keeping the data load on CH+S squarely in the users' laps (where it should be, btw).
I've been looking at some other clipboard managers, and for any of them that I'd actually consider using (mostly from an aesthetic point of view) they pretty universally keep the source formatting, with some of them maintaining multiple formats for each clip. There seems to be only one other that has gotten pasting plain text by keyboard shortcut right. You have an opportunity to rule for field here with this one. That said, I do want to point out one glaring problem I see for CH+S, and that is that it seems to be an utterly unknown quantity in the clipboard management field. Not a single google search result for "clipboard managers" I ran (typically filtered to a year or less) mentioned CH+S. Clearly a lot of reviewers are missing one of the biggest diamonds out there. None of the comments in these reviews ever mention CH+S either. Suggestion: run a similar google search and reach out to the reviewers letting them know that they have missed something really good on their lists.
IMHO, the addition of a hotkey paste-as-plain-text, and retention of source formatting would make CH+S better than all the rest. One possible exception, but a little competition is good.