Ion-Item ng-repeat contacts very slow to scroll

Hello , i’ve a problem with my app .
I have a $scope where inside , are stored the contacts in the address book .
When the contacts begin to be 400 , the scroll is very slow .
How can I solve the problem ?

<ion-item ng-repeat="item in contactsList" ng-href="#/app/contact/{{}}">
<!--  <span class="item-row-span blue-1 abs top-left circle-image mask" > -->
    <span class="item-row-span t title blue-2-c">{{item.title}}</span><br>
    <span class="item-row-span t grey-4-c t-small">
        <i ng-if=" != null" class="ion-email"></i>
        <i ng-if=" != null" class="ion-chatbox-working"></i>
        <i ng-if=" != null" class="ion-ios-telephone"></i>
    <i class="item-row-span ion-chevron-right arr-right abs middle-right"></i>

use collection-repeat instead of ng-repeat

Thanks very much , i’ll try !