If you experience crashes on Domino Designer, especially when dealing with XPage development, you might find this helpful.
# @NOTES_PID@ vmarg.Xmx=-Xmx1024m vmarg.Xms=-Xms512m vmarg.Xmca=-Xmca512k
If your PC has 3GB of RAM or more then you MUST do this! Open the file
<NOTES_PROGRAM_ROOT>\framework\rcp\deploy\jvm.properties
and change the first 3 lines to the setting above. Make sure that the first value is a 1/4 of your memory, but not more than 1024. The other two values should calculate to the half of the first value (512 is the maximum).
The result: your Domino Designer will work very stable. The crash frequency is tamed to a minimum - trust me!
UPDATE
Be careful to change those values with Notes 9.0.x as this may result it in too big heaps and maybe also screen flickering that I had after changing that values to the former ones!
These are the default values in 9.0.1 now:
Thanks to @TweeterDonnelly for the hint!