[Fixed 1.,15][Performance 1.14] loosing performance over time and fps-drop

While working on the last achievement just loaded a savegame and kept it running w/o building but looking into Car Stock and Car Designs from time to time.
Within 1 hour the fps drops from around 60 fps (zoomed in)/ 50 fps (zoomed out) to below 40 / 35 fps.
The cpu utilization still looks good:

When trying to place a new slot at this time the fps drops down to 10 fps. A video of this drop is available at youtube.
This also happens when placing a slot that do not need any components/materials, e.g. Research Office.

It’s a regular map without any modifications.

Because the game crashed at (manual) save, I needed to restart the game, loaded the last autosave and went off for lunch. So one additional note:
When continuing for more than 1 hour the fps drops to 25-27 fps no matter if zoomed in or zoomed out.
Attached the debug files from after the lunch. Could save the game and quit to desktop in a regular way …
errors.txt (1.76 KB)
debug.txt (42.9 KB)
drawdebug.txt (8.02 KB)

Btw.: What does ‘Untranslated HRESULT [-2147024882]’ mean?

[Edit: 2017-03-28]
just some more pictures …
Before restarting the game it ran at 20 fps at zoomed out while the cpu usage was around 40%:

After restarting the game and loading the latest savegame the game ran at 36 fps with the same view and a cou usage of only 20%:

The last savegame itself has a size of 93,102,080 Bytes and when saving or loading windows shows the sandclock (the blue ring) when working on vehicles …
autosave.rar (936 KB)

Thanks for such a detailed bug report. TBH the save game format is not particularly sensible for high performance, although its very very helpful for debugging. At some stage I’m going to have to just accept that I need to re-engineer it substantially. That should be unrelated to any in-game performance issues though, which i shall also investigate.

Yep, the savegame is easy to read. And I know that cars should be sold and not be hoarded at the car stock ;o)

So back at the major issue of this report: I’m still hunting for the ‘Premium Production’ achievement, build up a new factory with only a single production line. The cars are selling periodically (total price of 35,032 $) and everything is running smooth.
The production line is not complicated and producing only a single car configuration (all in) so it should not get critical to the usage of each cpu core or anything else.

In this case the effect is much slower but after 7 hours of running whithout any interaction it looked like this:

When trying to place a slot at this point it ends again in a fps-drop to below 10 …

After restarting the game and loading the latest savegame it’s better again:

I’m not really sure but when I remember correctly the top left core in taskman was/is running the main thread.
Is there anything else I could provide related to this issue?