For the original Cities: Skylines, compare the same city and camera view, then lower shadows and level of detail before reducing resolution. If a large city or modded save is the problem, close memory-heavy apps and test once with Steam Workshop content and mods disabled. This separates a graphics limit from a save, mod, or memory problem before you reinstall anything.
This guide is for the 2015 Cities: Skylines, not Cities: Skylines II. Compare the PC with the original game's current Steam requirements before changing the settings.
Load the city where the slowdown happens, pause it, and choose one camera position. Note the population, active mods, resolution, and approximate FPS, then reuse that view after every change.
3
Lower shadows and level of detail
Open Options > Graphics and lower Shadow Quality and Level of Detail one step at a time. Apply each change separately and compare the same city view.
4
Test depth of field and resolution
Disable Depth of Field for one comparison. Keep the monitor's normal resolution at first, then try the next lower resolution only if the earlier changes do not make the city smoother.
5
Compare a small unmodded city
Start or load a small city without adding new Workshop content. If it runs well while the large save remains slow, city size, simulation load, mods, or assets are more likely than the basic graphics preset.
6
Disable mods and Workshop content once
In Steam, open Cities: Skylines Properties > General and temporarily enter -noWorkshop -disableMods in Launch Options. Test the problem save, then remove both commands after the comparison so your normal content can load again.
Close browser tabs, editors, and other memory-heavy apps before loading a large city. Unsubscribe from assets you no longer need, then verify the Steam files if the game still behaves abnormally.
If the city improves with -noWorkshop -disableMods, remove or update mods and assets in small groups instead of deleting the save.
If a new unmodded city is smooth but a large city is slow, lowering textures may not help much because the simulation and memory load can be the limit.
If Windows reports that memory is almost full, close other apps and reduce unused Workshop assets before increasing virtual memory or installing cleanup tools.
ⓘ Sources and verification
Checked against official documentation on . Scope: Cities: Skylines on Windows.
The written procedure uses current official support information and visible in-game settings. If a label moves after an update, use the option's description and the linked official page rather than an old screenshot.
