I ran a test to compare how loading times may affect the IGT, and the results seem to indicate that the game does not take into account load times.

The way I performed the test was by installing White Day to a very slow USB 2.0 external HDD, and comparing its IGT to my usual SSD installation.

I used cheat engine on both to enable fast movement speed & saving without a pen in order to cut out as much gameplay as possible.

I started the RTA timer as soon as the loading screen comes in. (Keep in mind that means the opening cutscene just before the loading screen is missing from the RTA, but that's not important for this test.) The RTA timer ends the frame after confirming to save the game.

Anyway, here are the results:

USB 2.0 HDD: 22.57 (RTA), 11.00 (IGT) SSD: 11.08 (RTA), 10.00 (IGT)

The HDD installation was twice as slow RTA, but the IGT is essentially the same. The 1 second difference could easily be put down to slight differences in my gameplay. (In fact, you can see my menu navigation looks slower in the HDD test).

There may be factors I failed to control for which could make the results unreliable, so do let me know if you think of anything like that, but this does seem to indicate load times are not included in the IGT.

I wanna clarify that the results are probably a good thing :) If true it would mean that hardware isn't a factor in your time