Both, yes. The second one depends on your configuration, and your configuration depends on your hardware and your use-case. For example I have some 4GiB VPSs w

Both, yes. The second one depends on your configuration, and your configuration depends on your hardware and your use-case. For example I have some 4GiB VPSs with a single vCPU and slow IO, so I configure the virtual memory to aggressively compress unused ram with lz4; decompressing them takes no CPU power and is orders higher throughput and lower latency than any disk swap can ever be, even when using just 1 vCPU. Then it means I have gigabytes of RAM that is used as file cache, instead of wasting that space with unused ram, and when everything is needed at the same time it just drops the cache. Having all that cache availability also means that it can take in a lot of files without locking up. The first one also happens when you have too much RAM allocated for your things. When it's temporary until your applications finish it'll swap around and slowly finish eventually, but depending on your over-allocation and your swap's speed it can take significantly longer.