Roughly how long does a CPU Context Switch (swapping threads/processes) take?

A 'Context Switch' occurs when the OS stops one thread and starts another on the same CPU core. This involves saving CPU registers, flushing the Translation Lookaside Buffer (TLB), and loading the state of the new task, which typically takes about 1-5 microseconds. While this sounds fast, it is 'eternity' compared to a single CPU instruction (0.5 nanoseconds). If a system is forced to switch contexts too frequently (hundreds of thousands of times per second), the CPU spends more time 'managing' the work than actually *doing* the work—a state known as thrashing. This is why highly concurrent systems often use 'thread pools' or 'async task workers' to minimize these expensive swaps.