Memory – Understanding RAM Usage in Windows 10

4Gb DDR2 sticks are available(but quite expensive) and there are even bigger server ones.

This is a totally normal state of operation. Windows is quite hungry for memory (in comparison to e.g. Linux). So something between 1.5 and 2 GB for a running Windows 10 system is completely usual, at least in my experience. Unless your system runs out of memory, the memory usage doesn't make much a difference, performance-wise. Furthermore, most graphical applications use plenty of memory these days, so even if you might free some additional hundred megs of RAM, this won't do much of a change.

If you still think your system is slow, look into other parameters. Most Windows systems I get to see are bloated with lots of software running in the background, most of which I'd consider ransomware. So check your installed applications in the Control Panel. Second, the Hard disk is often the bottleneck in today's computer systems. The CPU can't get to it's full potential, because reading files off the disk is slow as heck. So consider getting a SSD if you don't have one, it might boost your speed by multiples.

And if you feel like you're running out of memory too fast, then get more memory, instead of squeezing every last MB out of your idle ram usage. Even in portable computers, memory still tends to be replaceble / upgradable, and it doesn't cost too much.