> However, this mode switching is expensive! Just this switch alone costs 1000-1500 CPU cycles in pure overhead, before any actual work happens.

...

> On a 3GHz processor, 1000-1500 cycles is about 500 nanoseconds. This might sound negligibly fast, but modern SSDs can handle over 1 million operations per second. If each operation requires a system call, you're burning 1.5 billion cycles per second just on mode switching.

> Package installation makes thousands of these system calls. Installing React and its dependencies might trigger 50,000+ system calls: that's seconds of CPU time lost to mode switching alone! Not even reading files or installing packages, just switching between user and kernel mode.

Am I missing something or is this incorrect. They claim 500ns per syscall with 50k syscalls. 500ns * 50000 = 25 milliseconds. So that is very far from "seconds of CPU time lost to mode switching alone!" right?

Read further. In one of the later benchmarks, yarn makes 4 million syscalls.

Still only about 2 secs, but still.