Ionic - AlertView Dismiss - SLOW

i have an application that uses alert views but the process to dismiss them is very slow.

Here I have posted a performance schema. There is a time where no operation is executed and the backdrop showed. Where is the problem???

These are my project configurations

cli packages:

@ionic/cli-utils  : 1.8.1
ionic (Ionic CLI) : 3.8.1

global packages:

Cordova CLI : 7.0.1

local packages:

@ionic/app-scripts : 1.3.7
Cordova Platforms  : ios 4.4.0
Ionic Framework    : ionic-angular 3.2.1

Thanks in advance

I have solved. In my app.scss I had the override of a class as shown in this code

ion-backdrop {
opacity: 0.5 !important;

After I have removed this piece of code, I had no more problems.

This is the new performance schema