Hi.
I play in large, beautiful world (Setra) in which live lot of sims (about 200). Unfortunately my computer is't new and often i have lags.
There is some mod to set max population in town?

Population is managed by whatever system is creating the sims to begin with.
1) Inactive residents are managed by your story progression system
- Progression mods, either tuning or scripting, can alter this system
- You can also manage this population by reducing the number of eligible residential lots you have in town
2) Service sims are managed by the EA service tuning
- There are tuning mods available to restrict the number of these sims the system attempts to create
3) Role sims are managed by the EA role manager
- You can reduce this number by reducing the number of role giving objects you have in town
4) Homeless sims are created by error, or by the EA Careers system
- There are cleanup mods, such as [Overwatch] that can delete these sims on a nightly basis.

You really should have a look at the demographic breakup of your town population, and see where the fat can be trimmed.

Twallan's Story Progression is best for this.

Story mods like Twallan's SP and the Awesomemod both have population cap you can set (I set it to a hundred). Of course in your case it's too late, the mod will only forbid the townies of breeding and your game will still lag until most of them drop dead from old age. I actually had the same problem (i.e. before discovering the population cap lol) and was forced to move my family to a new town as the lag became unbearable and I couldn't wait for the townies to die. Even randomy clicking on NPC and choosing a random death didn't accelerate the process. The move was a good choice, I didn't regret it at all.

If you already have too many and use use Twallan's Story Progression, you can use "total annihilation" at the courthouse and pick people to kill off in a list.

Thanks all
Twallan's Story Progression helps me