memory clogging up and render times go through the roof!

I have a project with a large number of nearly identical comps. Each comp has 90+ layers of the same video time-remapped to different frames. When I render the comps everything is pretty manageable to start with, the first couple in the queue will take about 2 mins to render but as the renders progress they get slower and slower until what should be 2 min is taking over an hour!  The machine has 64GB of RAM which Ae steadily fills up but then can't seem to manage properly once full. The only way to flush the memory is by quiting and restarting Ae. This is a total pain as it means babysitting the renders and having to restart Ae after every 5 or so renders in the queue. So much for the overnight renders...

I tried writing a simple script that would purge all memory between renders but this doesn't help at all, watching the memory consumption in the task manager shows only the most minor drop in memory being used by Ae.  The only way to properly clear out the RAM use is to quit and restart Ae.  I also looked at getting a node.js script to drive after effects i.e. opening and closing every 5 renders but it was a beyond my coding skills, doh...

Any suggestions or cunning ways of forcing AE to properly purge the memory between renders would be very much appreciated.

specs: Ae 2024, Windows 10,  i9-7940X, 64GB RAM, GTX 3080