Hi @sidzhere
My second PC had more or less the same specs as yours. 4 gigs of ram and a very basic graphic card.
I used it many times to work on 1920 x 1080 projects. Reducing memory usage, like @Hudson555x suggested, plus using Preview Scaling AND Proxies helped a lot. It was not super smooth, but manageable. And for parts of the projects where there was too much lag to preview in Shotcut, I used the Copy to Timeline option in the Timeline menu. That allows you to quickly export a small part of the timeline (part with heavy filters for example) and to preview it in an external media player without lag.
You can learn how to use the Copy to Timeline tool in this tutorial:
