Discourse recommends 1GB as the minimum and I have ran installations this way and it gets slow quick, therefore I would go with 2GB.
This first 2GB last a long mile I currently run a community with ~3500 visits/day without Crawlers and some 20-30 posts per day I haven’t seen any issue with the 2GB of RAM and haven’t noticed any slow downs.
I’m almost sure @AntiMetaman that your issue is with the Bitnami image and not resources. Make sure you CPU is fast enough and if you’re able give it a second CPU (I only use 1vCPU and does the job).