Game very laggy

Hi.

My game is an open world game and its using World composition. I broke up the map into tiles and each tiles has 150 - 350 static meshes. When i hit play in editor it takes 4 - 5 Minutes to open the game window an then its still very laggy… when i move around the map and the engine begins to load a new tile the game hangs again 2 - 3 minutes. So i cannot properly test my game. How can i test my game without lagging? I have read that the solution is to package the game before testing. But this takes every time 5 - 6 hours. I dont want wait every time 6 hours before i can test my game. Is there any other way to speed up the load time or to test my game without waiting 5 minutes and laggging?
Or is my pc to weak for this?

Hardware
CPU: AMD Ryzen 5 2600
RAM: 16 DDR4 2400 Mhz
GPU: AMD Radeon RX 580 8 GB GDDR5
HDD: 1 TB
OS: Windows 10 Pro 64 bit

It sounda you hiting some ensure condition, check the logs (Window->Devlopment Tools->Output Log or text file in your project directory in Saved/Logs), if it’t ensure it should sump you the exception that is the cause. Check the log anyway it might in general hint you to the problem

I have already checked the Logs but there is nothing in there… no errors
There must be a way to test large open world maps without cooking everytime the whole project for 5 hours/ waiting 5 minutes to open up the map and then to wait everytime again 5 minutes to load each tile from the map…

How handle this other developers thar are develop open world games with ue4 without lagging? How they test their games? I dont think thay they coook the whole game everytime…

Makes me wonder if you are loading the levels more than once, like on a timer or event handler that fires more than once or something. However, that would not explain the really long build times at all.

You don’t have this problem with other projects, right?

no, i just using the world composition function in world settings in my persistent level, the tiles are automatically loaded by the engine

How Many polys are in a tile on average.

~350.000 on average