I'll admit that I have no real experience with garbage collection (outside Perl) and little technical knowledge of it. I'm just going by what was referenced in the request itself. One was a 1998 survey that, under "Mark and Sweep" says:

"As with all tracing schemes, once GC is started, it has to go through all the live objects non-stop in order to complete the marking phase. This could potentially slow down other processes significantly, not to mention having to stop the requestor process completely."

You must be talking about something other than "mark and sweep" (which is what the suggestion proposed) or your definition of mark and sweep doesn't match that of the survey.

If this is using concepts that are 20 years out of date, then a link to more appropriate reference material would be appreciated.