Odd Location for Loading Time Increase

[zippy57]

I'm trying to track down an odd issue that causes the load times on my game to increase exponentially if a specific mod is enabled in conjunction with another specific mod. I have not yet located the second mod in question but I have confirmed that is what is going on. For the purpose of knowing what to do with the second mod when I find out what it is, I have a question:

 

What is Skyrim doing between confirming the loading of a game on the main menu and the switch from the main menu to the loading screen and/or the display of the "missing plugins" message?

 

I have a large load order and so long load times are expected (occasionally approaching a full minute to load a game, especially one saved outside) but this particular issue is not only exacerbating that to a factor of eight but also creating a 22 second gap between the direction to load a save and the missing plugin message (without the problem plugin this takes approx. 2 seconds). Having never seen that behavior before makes me think that whatever is causing that issue is the same thing that is causing the other load issues.

 

Also possibly relevant: During the load times affected by this issue, the game spends a large amount of time pulling something into memory without reading from the disk (approx. 3-4 minutes). Under normal circumstances it does this only for a few seconds before starting to read from the disk. The amount of time the game spends reading from the disk remains the same; only the time where the game is not reading from the disk is increasing.

 

EDIT: Making the plugin in question an .esm solved the issue completely. Anyone have any idea why that would be the case?