Click event slow IOS with list over 20 items

I have this ionic 2 app, with a modal page, with a list of rows. one of the gestures is double click to action a row and refresh the data. this is a file browser type UI. , you can also select one or more rows (files) via click.
so there is a click handler and a double click handler per row,

sometimes the list is 10 items, sometimes over 100… it scrolls to show additional data.

on android, note 3, double click works fine regardless of how many items are in the list
ipad Air, the click handler is real slow ~5 seconds, when the list is over 20 items. and double click never works (timeout is 400ms)

i added a press gesture as a workaround to not being able to double click, but that seems unnatural

is this a device performance thing, or an IOS thing, or a page design thing?

the modal page

<ion-header padding width="100%">

  <ion-toolbar>
    <ion-title>{{dialog_title}}</ion-title>
  </ion-toolbar>

 	<ion-row>
 		<div class="col dashed-border" >{{parentpath}}</div>
	</ion-row>      
	<ion-toolbar no-padding>
		<ion-row >
			<ion-col col-2  class=" colb  center">Select</ion-col >
			<ion-col col-2  class=" colb  center">Type</ion-col  >
			<ion-col col-8  class=" colb ">Name</ion-col>
		</ion-row>			
	</ion-toolbar>     	
</ion-header>
<ion-content padding  width="100%">
 <!--- file modal here --->   									
<ion-row  *ngFor="let file of files; let i = index" (click)="setClickedRow(i,'file','any')"
                       (press)="doubleClick(i,file)"> 									 
	 <ion-col col-2 text-center class="colb " no-padding >				 					
		 <ion-checkbox  [(ngModel)]="file.selected" (click)="setClickedRow(i,'file','any')"></ion-checkbox>  
	 	 </ion-col>
	 <ion-col col-2 class = "colb center" >{{file.filetype}}</ion-col> 									 
	 <ion-col col-8 class = "colb" (dblTap)="doubleClick(i,file)"   
			no-padding>{{file.name}}</ion-col> 
	 <ion-col col-0 style="display:none" >{{file.id}}</ion-col> 										 													
</ion-row>										 

</ion-content>