Nothing to do with Aeotec : SmartThings is still providing the app and the cloud. Aeotec is only taking over support of the physical devices which are sold with an Aeotec logo.
An Update Regarding our Hardware
But, yes, a lot of people have noticed increased slowness recently. 
Slow Zwave, and getting slower
.
Is the new ST App super slow? Or is it just me?
.
New app very slow to come up
.
Slow response to motion/triggers
.
New Android App 1.7.60.23 January 27