After Effects (and Media Encoder) RAM not freed after project closed (specially with expressions)

Hi everyone,

We've noticed a weird RAM behavior in After Effects 2020 (17.5.1 - Build 47) and Media Encoder (14.0.1 - Build 70). When closing and opening a project multiple times, After Effects’ RAM usage is continuously growing especially when the project contains expressions (even the simplest one). Closing the project and purging memory (and Disk Cache) do not reduce the RAM usage! The only way to make the RAM usage drop seem to be closing After Effects! The same problem exists when sending these projects to Media Encoder. The RAM, used by the After Effects sub process under the Media Encoder main process, continually grows and does not drop even when the rendering process is complete.

We already know that expressions can be RAM consuming but the fact the RAM is not freed after the project is closed seems not normal.

We tried to reduce the case to the simplest situation and made a benchmark. The details of our benchmark can be found here :

https://docs.google.com/document/d/1NEiyg-mKzBIOBioCOGqoJT4_DDG-U4Tf5dgrNbnXI-o/edit#

The quick conclusion is that after 20 openings of the simplest project (one comp > one solid layer) the difference in RAM between no expressions and 2 very simple expressions (basically setting the layer's position to its own position "transform.position" and scale to its own scale "transform.scale") was about 0.5 Go ! (2% RAM increase for no expressions and 74% RAM increase for the simple expressions) Again more importantly RAM that is not freed when the project is closed !

Is this a known issue ?

Thanks for your help.