How can I get into the client faster?

It can take a while for the Ingress client to start. There's an initial loading screen, followed by the "acquiring user" screen, followed by a few seconds of waiting for the client to determine my position. Is there anything that can be done to cut down on all of that startup time?

Note: I'm providing my own answer below, but I hope that won't dissuade anyone from also answering.

Solution 1:

The "Ingress Wake" app works like a wrapper around the Ingress app to keep it active even when the screen is locked.

Solution 2:

Although there's no way to skip the initial loading screen, it is possible to skip the "acquiring user" screen (shown below) by pressing the Back button on your phone while it's being displayed. This will shorten the loading time by a few seconds.

Solution 3:

What I use, not to speed up startup but to accelerate GPS localisation when coming back from sleep is GPS Widget.

It will keep GPS up and locked on position, so when coming back from sleep will avoid the "Scanner disabled, location inaccurate" phase.