Thanks for the reply, Atul. With the migration to grails3 we had a look into Spring boot (it's now a essential part of Grails 3 environment) and it's tools, most notably the Cloud part, where Netflix shared a lot of good code. We started to separate things with Eureka server, Cloud config, Hystrix/feign and the likes, but the memory problem became more apparent (not in any way with Spring boot and Netflix solutions, it's pretty slim btw), but with Grails3 and some attached libraries. With the first separation, now we have two fat apps running... and that's the point, we couldn't find a reason why our app is eating 1GB+ of memory. Other answers on Internet says to add more RAM, but it's like a rocket not escaping gravity of earth... add more boosters? =) So our best bets are to try, get some small parts and rewrite them one piece at a time, get the feedback and see how it goes. Thanks for sharing your thoughts.