Android - How to make camera start faster

Try InstaCamera Pro from Google Play Store. It starts very fast and has preferences to start camera and takes photo just by a single touch from home screen of your phone:

InstaCamera is the quickest way to take a photo with your phone.

There's no long process: just press the widget and it takes a photo, then closes just as quickly.

The paid PRO version is supposed to be faster than the free version.

If any app takes significant time to open, it means that app is heavy on resources and/or there's high load on system. Before bringing any app in memory, Android first makes room for it in memory (technically, it happens based on minfree value even if there's room for that app).

So, to solve the issue, do these things:

• Reduce load from system. Less running apps in memory means less probability of minfree based ju-ju.

• Use a lightweight camera app. Lightweight apps are loaded in memory faster and again there's less probability of minfree based ju-ju.
  There are many lightweight camera apps in Play Store. Just, search "Fast Camera".