Massive performance issue with full CPU usage (< 100k citizans)

[Ma173]

Hey everyone!

First of all, my PC specs:

• Windows 10 64 Bit on a 840 Evo SSD (120 GB), last formatted a year ago
  
• Asus Z270 Mk2 Mainboard
  
• Intel i5 7600 with 3.89 GHz
  
• Nvidia GTX 1070 Windforce OC
  
• Cities Skylines running on a Samsung 850 Evo SSD (250GB)
  with the DLCs Mass Transit, Snowfall, After Dark, Match Day and Pearls From the East installed

I currently have less than 100k citizans (currently 93k) in my city and play this savegame for some time but not that long (it's 2036 ingame). I'm using some workshop content but not excessively much and have a low amount of mods activated that don't seem to bother the game (I could list them up if they'd matter later).

The thing is, the game actually slows down my PC completely. The game reaches up to 92% CPU usage (says the task manager) which with all other processes sums up to a constant 100% cpu usage when the game is running. I only have Spotify running alongside Cities Skylines. It even makes the music get stuck sometimes - and typing this text while the game runs on my primary screen is exhausting as typing outside CS has a massive delay.
Even ingame, the camera sometimes does not rotate smoothly and the sound sometimes lags.

How can all this happen with such PC hardware and not that many citizens compared to other players having performance issues on quite an other level of population?
I can understand that the game might consume a lot of CPU which leads to the displayed value in the task manager but really no chance to have anything running alongside the game? People on Discord even lag horrifically when I'm ingame.
Other games as challenging like Planet Coaster don't affect the whole Windows system that much

Thanks to everyone who can give me a clue of where the problem could be! :)

[ionice]

Try lowering the resolution and increasing the priority of the game in the task manager.
If this issue is specific to this one savegame, It could be caused by props or traffic, malfunctioning asset ( absurdly high resolution model/texture, obscure filtering & etc ) or outdated mods.
There are mods that tackle common performance killlers, Not saying they'll fix your problem but they're worth a try.

I'm interested what others have to say :) Good luck.

[MarkJohnson]

If it is a continuation of your 2-year old, Megapolis_MA173 on your workshop page, then it is likely a workshop issue.

Your output log shows all mods are outdated. either deprecated, WIP, abandoned, not working, replaced, etc.

Maybe post a new save of the city for us to look at. The old save doesn't work properly with the new version of the game for workshop purposes.
We can advise on replacement ones if applicable.

[Ma173]

Thanks for the comments so far :)

It's not the savegame I uploaded years ago :D I started this new one some weeks ago.

But you are right with the mods. I tested the same savegame after starting the game with the "--disablemods" option. Then the game runs super smoothly.
So now the tough question is - what mod is it that makes the game go nuts?

When I started the savegame with "--disablemods", some (3 or so) assets got displayed as broke - are they automatically the problematizing ones?
I'll check out the mods tackling performance killers anyways.

Thanks again, I'll keep you updated

[MarkJohnson]

Did you unsubscribe to all of your mods before starting a new city and resubscribe new ones? If you left any of the old mods in there, you will likely have issues with those old ones.

[Ma173]

No, I did not unsubscribe to any mod previously installed before I started a new city.
I did not know this was needed :O

[Ma173]

I now unsubscribed from all assets that got displayed as erroneous when loading the savegame. I also unsubscribed from all content that was marked as with too many 'details'.
I deactivated all mods that I found not necessary and that my friend who's savegame works fine does not have.
Still, the game does not run any smoother (noticably) than before. I can't find the mod (compared to "--disablemods") :/