You're not the only one anitpode.
That being said, the best way I have found to mitigate (i.e. get back into the game ASAP) this issue is as follows:
- You will know within 3 seconds of "entering the loading screen" whether or not the load was successful (I.e. there will be a large "League of Legends" icon in the centre of your screen if you alt tab out, the screen will remain dark if you are tabbed IN, and your cursor will remain your default cursor)
- Alt+F4 to force-exit the game/loading screen, which will automatically re-open the PVP.net client
- Click reconnect (note: the reconnect button may grey itself out for a couple seconds after clicking... this is to be expected)
- Re-enter loading screen.
- Return to step 1 if necessary.
I have been able to get into most of my games in a decent amount of time using this method (although it is still annoying to get into lane 1 level behind sometimes).