iOS app slider jumping after dimming homematic light, due to long refresh rate?

When choosing a dimming value with a slider within the iOS app after releasing the slider it jumps immediately to the old value and after two second to the new value. Dimming of the real light is nearly immediately. Why does the slider update the old state and does not save the new state. Waits 2 seconds for update and then syncs the real stat when necessary? Or why is the update time so long.
And why does the slider not send update commands while sliding? But after releasing the slider. Would be easier to choose a dimming state.
At the web interface the update is immediately!

I’m using OH 1.8.3 on a fast Synology Server 716+, CCU2, Homematic LED-Dimmer and other Dimmer.

Can I change the behavior by changing a refresh value or something like this? Can a developer improve the slider widget?