If you run into a Java heap space error or get an OutOfMemory error you can increase the amount of allocated memory for openLCA in the preferences.
In the menu, select 'File -> Preferences', in the dialog select 'Configuration' and specify a new value for 'Maximum memory usage in MB', e.g. 4096 if you want to assign 4GB.
For the changes to apply, you will need to restart openLCA.
If you still run into problems, you can try to disable logging in the 'Logging' tab of the preferences, by setting Level to Info, unchecking the 'Show log console' box and closing the 'Console' tab afterwards.