I believed the kinux kernel recently became real time?

Just because a CISC will run multiple instructions in a single clock cycle, it doesn’t automatically make it faster. Complex instructions means complex decode logic, that makes the execution slower, even at the same clock cycle. A modern intel CPU has something like 20+ stages of pipelining, while ARM has 3-5 stages, that makes the execution more energy efficient and more powerful. Also superscalar RISC architectures exist, so RISC can also execute more instructions at a time, and in less time.

Lastly, modern x86_64 look like CISC, but are actually RISC under the hood, the single instruction is just a pseudo-instruction divided in multiple simpler instructions. I don’t believe thay makes it much more efficient.

At least if you install other apps you already have KDE. If you install another Flatpak, it’s likely this will need another version of the KDE runtime, so it’s 2.5 more GB for a 450kB application.