Apple’s latest mobile operating system was released a week ago, and according to Apple, it reached 46% adoption rate in just five days. Although it is packed with new features that make upgrading tempting, iOS 8 is not quite where it supposed to be yet in terms of stability, according to Crittercism (via ZDNET).

The latest report from the market research company says the iOS 8 crash rate is 78% higher than iOS 7. After analyzing data across iOS users between September 17 and September 22, Crittercism found that 3.57% of apps crashed on older devices such as the iPhone 5s, iPhone 5c, and iPhone 4s.

By comparison, the crash rate is only 2.63% on the iPhone 6 and 2.11% on the iPhone 6 Plus.

Before the iOS 8 release, developers had stabilized crash rates across iOS versions: iOS 7.x had only 2.1% crash rates, with the iPhone 5s crashing the least of all iDevices, and the iPad mini crashing the most.

This sounds like another reason for iPhone 4S owners to wait for the iOS 8.0.1 update, which will likely bring more stability.