Open Radar

 
Summary:
Navigating to Spotlight is sluggish / drops UI frames.

Steps to Reproduce:
+ Begin on the first page of apps in Springboard
+ Pan on Springboard so that roughly half of the first home screen, and half of Spotlight, is visible
+ Pause in this half-home-screen, half-Spotlight state
+ Release finger

Expected Results:
Springboard either returns to the first home screen, or moves to Spotlight, depending on where the pan was released. It does so in a smooth and fluid manner.

Actual Results:
Springboard drops frames and stutters for ~0-0.5 seconds, and then performs the expected behavior

Regression:
+ Occurs on iOS 9 beta 2 on an iPhone 6 Plus. Have not tested on other devices. 
+ Does *not* occur when swiping / panning quickly between the first home screen and Spotlight.
+ Does *not* occur when performing the same actions, starting at the Spotlight screen
+ Actually occurs any time any portion, even a tiny portion, or a very large portion, of Spotlight is visible navigating from the first Springboard app screen.

Notes:
Related to rdar://21358170 , which describes generally sluggish performance navigating to Spotlight, but rdar://21358170 seems to have been partially solved and performance has generally improved. The problem described in this bug report still exists, though.