But for others, who have older machines, it is a very real problem. One of the good points of GNU/Linux is that one does not have to keep upgrading one's hardware when software upgrades take place or when a distribution moves from one version to the next.
In recent times, GNOME has lost some traction, especially after the release of version 3, when it moved to a desktop design that resembles the interface of a mobile phone. KDE lost some traction when it released version 4.0 some three years ago, but that loss has been largely forgotten as it has fixed all the problems which that version had.
But still, using either desktop environment on older hardware does tend to slow things down - at times, unbearably so.
Here is where a desktop like the Lightweight X11 Desktop Environment comes in. It is not half as well-known as KDE or GNOME but an excellent substitute.
LXDE is fast, has plenty of features, and is very stable. Strangely, I had never heard about it until March this year. Simply put, being a long-time GNU/Linux user, I settled on a desktop environment of my choice and, once one has done that, one tends to stick with it if it does not get in the way of productivity.
On my PC everything has been fine; KDE works well and allows me to do what I want even though it is now into its sixth year and has only a single-core AMD64 processor. But on my laptop, a Thinkpad which is in its seventh year of use and has a Pentium M 1.70Ghz processor and 2GB of memory, I experienced some instability earlier this year.
I was using KDE and the desktop failed to load after an upgrade. At the time it happened, my workload was such that I had no time to fiddle and find out what was wrong. I looked for the easy way out, a DE that would allow me to keep working.