Best way to setup 2 files on the same FMServer as external data sources for each other?

[cincin]

I have two files that I serve from the same FMServer 16 instance. They both need to access data from each other, so I have them setup as External Data Sources of type FileMaker, with a single path like this:

file:FileName

I'm having occasional problems, in both files, from FileMaker Pro 16, with delays accessing data from the other. I get occasional "Find in Progress" progress bars that last quite a while. Considering the files live on the same server, I expected it to be pretty quick.

Am I not doing this properly? Is there a faster way, short of merging the two files into one?

Thanks!