How much time it usually takes to switch Android runtime in KitKat? I have Dell Venue 3830 and I plan to change its runtime from Dalvik to ART. It has Android KitKat 4.4.2. I have 12 gigs of apps.

I want to try ART so I want to know how much time it takes to switch Android runtime?
This is hard to predict, mostly because not all apps work the same. I remember switching my Galaxy Tab 2 to ART took about 15-30 minutes with 183 apps installed.

How long this process takes largely depends on how many apps are installed and how fast the processor is. Most likely your device does not need to work through 12GB of data: it only needs to work the executable portion of the apps, not the stored images or cache.

I would say switching to ART would take up to 20-30 minutes depending on how many apps you have installed.