Pinning the home screen
NOTE: Requires root access to your phone.
Do you find that your Android takes a long time to return to the home screen? That's the screen with the icons and various widgets... it may even present the "Force close/Wait" dialog before the screen is fully drawn. The Android OS manages memory carefully, and stops and starts applications as necessary to keep things running. Just because an application appears to be in the foreground doesn't mean it is running, and just because an application is not visible doesn't mean it is not still running.
One of the reasons for the home screen to take some time to display is if that application has been stopped to make room for others. However, there is a simple fix - tell the Android OS not to stop the Home process. From a root shell:
# setprop ro.HOME_APP_ADJ 0
If you want this change to be permanent:
# echo 'ro.HOME_APP_ADJ=0' >> /data/local.prop
See /init.rc on an Android phone for more variables, and frameworks/base/services/java/com/android/server/am/ActivityManagerService.java in the Android source for how these are handled.