Shared Mode
config.xml :
<preference name="xwalkMode" value="shared" />
Multi-APK Mode
<preference name="xwalkMultipleApk" value="false" />
Optional: Java Heap Size
environment variable :
_JAVA_OPTIONS=-Xmx512M
References
https://taco.visualstudio.com/en-us/docs/cordova-crosswalk/