That's KDE Dolphin, has been improved a lot over the last few years. KDE in general has been in good shape, better than GNOME 3 in my opinion. I've been using

That's KDE Dolphin, has been improved a lot over the last few years. KDE in general has been in good shape, better than GNOME 3 in my opinion. I've been using GNOME 2 and GNOME 3 (up to 3.8 when they completely got rid of fallback mode) for about 10 years, always felt that Nautilus as a file manager was basic and useless. I switched back to KDE 4 (AFAIR it was 4.10 at that time), the desktop search and index implementation - NEPOMUK (what a bad name) had big performance issues when doing the inital indexing and when it does periodic indexing the desktop simply choke. It took a while to search for tips and best practices to settle it down. Later on I decided to completely disable that as I don't need it... Later on KDE switched to a new search and indexing engine called Baloo, it seems that the design is better and configuration is more straightforward but I still cannot justify, disabled ;-) In short, have been running Linux as my main desktop / workstation OS for 15 years, I come to a conclusion that OOTB (most distros) setup is not ideally optimized and secure for Linux Ninja, it takes time and effort to tune the system to suite your personal standard / taste (Now I run Arch Linux on most of my devices).