If you experience crashes on Domino Designer, especially when dealing with XPage development, you might find this helpful.
If your PC has 3GB of RAM or more then you MUST do this! Open the file
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!
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!