Deprecating a history splitter

I'm in a situation where a mirrored history DB is being shut-down, and I actually need to deprecate a history splitter. I have some scripts that will opportunistically adjust the history provider of all the tags from the splitter to the remaining DB connection over time, but I know there will be stragglers and possibly some tags that the script misses, so I'm planning on keeping the splitter available for now for full coverage.

Is there some preferred way to have a splitter in place and minimize the load when only one path is being used? For example, is it better to point the deprecated leg of the splitter to a disabled history store or to a internal historian with a super-short time limit or something else?