128mb is a lot compared to go which will often run around 10mb. Was your jvm back then 32mb or 64mb? If it was 32 your memory requirement will be higher on 64.
128MB was the total RAM in the VPS including OS + nginx + JVM + Postgresql. The heap allocated to the JVM process was about 64MB, but bear in mind that this was an actual application. So, it's hard to do a detailed comparison between JVM and Go without standardising on the application. All that I am claiming is that JVM is in the same ball park.