Here is a brief report of my testing so far if someone is interested. Thorium can actually be installed on such an old computer under Windows XP. The browser starts up still quite bearable compared to other browsers on my system. However, as always with Chrome browsers on low-performance computers under Windows, the page loading behaviour is problematic. Although I have configured all conceivable flags to increase performance and selected the settings to suit my hardware, loading web pages takes considerably much longer than with New Moon, Serpent or Mypal. Of course, websites can be loaded that no longer function properly in the already mentioned browsers. Surprisingly, RAM consumption is not a problem, it is rather perfect although Thorium is running in multi-process mode. Interestingly, it seems that I have even found a solution for my installation that considerably speeds up the loading of web pages and therefore the browser start, too. It's not a new one, though. One doesn't have to reinvent the wheel, either. But first, this method must still be thoroughly tested.