Big chunk of that RAM is taken by the Android support. Killing it gives you 50% free, which is okay for a number of concurrent tasks.
As for the 1GB RAM PC - do you run a browser in it? It will swallow your RAM in one go, especially Chrome
--- | SailfishOS 1.1.7.28 (Björnträsket) (armv7hl) '--- [nemo@Dinghy ~]$ free total used free shared buffers cached Mem: 825664 725376 100288 0 6516 200052 -/+ buffers/cache: 518808 306856 Swap: 627516 102652 524864 [nemo@Dinghy ~]$ free total used free shared buffers cached Mem: 825664 570696 254968 0 6516 200416 -/+ buffers/cache: 363764 461900 Swap: 627516 102652 524864 [nemo@Dinghy ~]$