I am running AppSmith via a Docker install on Ubuntu 20.04 server in an AWS Lightsail instance with 2GB Memory.
It looks like running simple queries with 500 lines to display on a table makes the server RAM run low, and the app becomes laggy.
Is it a bug or expected behaviour?
What is the recommended HW server config to run AppSmith smoothly?
Answer from @sharat87
If I understood this right, you installed Appsmith on your server using the install.sh script provided in the repo, correct? This script will setup an running instance of Appsmith, complete with a MongoDB database, a Redis instance, an nginx server for frontend assets among other things. So, all these systems end up bringing the minimum requirements up by quite a bit. For such a setup, we currently recommend at least a t3.medium or a system with equivalent specifications for smooth operation.
The reason I gave this detail is, if you choose to say, move your MongoDB or Redis instances on other machines or connect to managed hosting provided instances (like MongoDB Atlas in the case of MongoDB), then the remaining services in your setup might just be able to work with lower resources. But of course, this will depend on how much has been offloaded to other systems and how many services are still running on the server that’s also running Appsmith server.
Would you say that memory or cpu is more important? (assuming the instance is already running on fast local ssd, so IO can’t be improved).
From what I’ve seen, the load is more general-purpose, than compute-intensive or memory-intensive. So, I’d pick something that’s not entirely focused on one of those aspects and foregoing the other. I suspect it’ll also depend on the usage style. In the sense that, do you have a lot or applications and users that are fairly simple in nature, or just a few applications, that are huge and quite complex in nature. For the former, I think memory will be more impactful, but for the latter, compute might be more impactful.
But, like I said, this is from my limited experience, so, take it with a pinch of salt 
.