Slider widget will show up very slow

Hi Guys,
my OH version is: 2.2.0 Build #1072
I am using a slider for my homematic thermostat setpoint temperatur. Using the standard slider widget is working fine.
To control a few preset temperatures i added a button widget. Due to my window sensors i tried to disable or hide the buttons when the window is NOT closed. This works well and fast for my buttons.
So i was looking for a way to do this for the slider as well and created my own slider widget. This is the code:

<div ng-if="itemValue(config.windowstatus)=='geschlossen'" ng-init="sliderModel = { name:, item: config.item, floor: config.floor, ceil: config.ceil, step: config.step, unit: config.unit, hidelabel : true,bigslider:true}">
  <widget-slider ng-model="sliderModel"></widget-slider>
<div ng-if="itemValue(config.windowstatus)!='geschlossen'" ng-style="{'color' :'#B3B4C0','text-align': 'center','font-size': '20px'}">Fenster nicht geschlossen, keine Temperaturänderung möglich.

This works also fine, BUT the show up of the slider is somewhat slow in compared to my buttons. Please see this video to get a clue what i mean.
So if the window is opened the buttons and slider will hide and if it’s closed the come back again and this come back takes long for the slider.

This raises 2 Questions:

  1. Can i speed up the show up of my slider widget somehow?
  2. If the show up can not be tweaked, can i disable the slider somehow. Means, when the window is not closed my setpoint temperature is automatically set to 10°C. So i would like then my slider visible at 10°C but disabled for any interaction and then if the setpoint temp. is above 10°C the slider should come back to normal operation.