I think this mod is causing my save files to balloon up to 100+MB in size. When I disable this specific mod, it deletes a ton of stoplight entities and then the save file goes back down to 20MB from 100+MB.

Below is a progression of save files. Something happened right around the time when josh-1.1-h.zip was saved. I saved it because the map started lagging pretty badly so I thought it was going to crash. Now, when we resume this map and save the file seems to get larger and larger.

-rw-r--r-- 1 stan stan 5.6M Nov 25 20:37 josh-1.1-a.zip
-rw-r--r-- 1 stan stan 6.7M Nov 25 22:26 josh-1.1-b.zip
-rw-r--r-- 1 stan stan 8.5M Nov 26 01:38 josh-1.1-c.zip
-rw-r--r-- 1 stan stan 11M Nov 26 03:27 josh-1.1-d.zip
-rw-r--r-- 1 stan stan 13M Nov 26 17:28 josh-1.1-e-bad.zip
-rw-r--r-- 1 stan stan 15M Nov 26 21:56 josh-1.1-f.zip
-rw-r--r-- 1 stan stan 16M Nov 26 23:28 josh-1.1-g-bad.zip
-rw-r--r-- 1 stan stan 56M Nov 27 04:35 josh-1.1-h.zip
-rw-r--r-- 1 stan stan 150M Nov 27 15:22 josh-1.1-i.zip

https://drive.google.com/drive/folders/1eu5lTtjwfog6tJYCqopU_vzRYuRFeuAK?usp=sharing

It seems quite reproducible from the h or i filesave. If you load it without bottleneck, it will reduce the file size back to normal. If you then add bottleneck back again, after playing either the h or i save for a little while, saving it again will balloon the filesave again.

Sorry, this seems related to a different mod actually. I think bottleneck is not causing the issue. I think it's related to the construction drone mod.

Bottleneck would be a good candidate for this behavior, since it creates (and normally deletes) many new entities every tick, but I'm happy to hear that some other mod caused the issue.