Game lags so much when running the Build the 1st time, but smooth from 2nd time onwards

Hello, this is my first Unity forum post

My game has a certain UI feature that can run smoothly in the Editor. When built and run the .exe for the first time, the game lags very much when that feature comes up for the first time. But strangely, when the feature come up for the second time onward, or when I restart the game, or quit game then run the .exe again, the feature can come up smoothly without lag.

An issue may be related is that the Build also takes long time to load on first run, but load significantly faster from 2nd time onward.

Anyone has ideas of what is going on and how to solve this? Thank you very much for any help.

 

My first guess would be that your computer has a low amount of RAM and you're experiencing memory contents being swapped to virtual memory on disk, which would be even worse if your virtual memory is on an HDD instead of an SSD.

Beyond that, you should take a look at what the profiler says is going on.

 

I have 16GB physical RAM, though old DDR3 but should be more than enough I think?

Profiler is a good idea, let me try.

 

In Project Settings --> Player there is a setting near the bottom called 'Pre-loaded Assets'. Drag any laggy assets into those fields and it should clear up. Keep in mind this is probably just a quick fix. I recommend you find the true source of the lag or it will just come back later.

 

It is more than enough if you don't have a lot of other applications running that are using it all up.