We have released new versions of our SYNCING.NET mobile apps for iOS and Android.
No it is possible to sync thousands of contacts and events within seconds. As contacts and events are not updated frequently, you can disable check for updated contacts and events in the app. This can improve the speed of synchronization significantly.
6.3.12 SYNCING.NET for iOS
6.2.43 SYNCING.NET for Android
You can dowload or update the mobile apps in App Store or in Google Play Store. Links to the apps you can find on the Download page.