Huge lag spike on first touch due to Event System?

Hello! First time posting here, and unfortunately its due to a big problem we are having with our game.

We are basically doing a 3D third-person shooter, and things were running smoothly so far... except for one problem.

The game is a bit complex, so the HUD has many buttons - weapons, consumables, inventory slots, etc. They are all organized on a single canvas with a Graphic Raycaster. When i touch any button of the canvas for the first time, no matter what is the button, i get a huge lag spike, which wont happen again for the rest of the scene.

I did some tests by removing some Event Triggers, deactivating some HUD elements, etc, but the lag spike still happens even when we have only three buttons on the Canvas as soon as we touch any of the three.

Here is a profiler screenshot of a test we made with the full canvas, all objects working, where its possible to see how much the EventSystem.Update affected the FPS. Here is a second test, where we only had three buttons active on the canvas. The other HUD elements were completely removed from the scene.

I've search through the forum but none of the solutions i've found worked so far. Anyone knows a way to reduce this lag spike?

 

Bumb, 1st event system touch causes lag and GC alloc. Still a problem in 2018, simple 2d project does this

 

Did you manage to solve it?

 

any updates?

 

Hello, I still have this issue in the latest version. Any updates?

 

In my case, it was a call to DateTime.Now somewhere deep in the methods that was slow!
take a look at this:
https://issuetracker.unity3d.com/is...dot-datetime-dot-now-is-slow-on-the-first-run
I replaced the code with Time.time and it's fixed now.