So working away and (something like ) this popped up. Actually the one that appeared had 'Logos' in it and indicated that 'Logos' was 'paused'.

I'd never seen this before.
I quit Logos and opened 'Activity Monitor' to see what was going on! It looked ok!

So I restarted Logos and it popped into the middle of the list of running applications with no problem.
Then, from the side bar of the Home Page in Logos I opened the Revised Comon Lectionary and boy is this big!...

And up popped my warning and Logos had to be Force Quit again.
Here are some logos from just after the last 'Force Quit' and before restarting the app.
4606.LogosLogs.Mike.20161205-122711.zip
Just a couple of late additions
On the stable version on my MacBook - Home Page shows at about 500MB of space - RCL layout (other items also open) moves the readout in the Activity Monitor it to 606MB
On the desktop (beta) the home page us also using about 500MB but opening my RCL layout makes the Activity Monitor read 80GB as it runs out of memory.