Hi Olivier,
I think you can modify vmarg.Xmx of deploy\jvm.properties file in the Notes
9 installation package. After upgrade to Notes 9, the new vmarg.Xmx property
will be written into NOTESDIR\framework\rcp\deploy\jvm.properties. But
it will also overwrite the original jvm.properties file. So if you have
any customized porperties in previous jvm.properties, you need to merge
them in the file of Notes 9 installation package.
Hope this helps.
Qi Ming