> The difference with manual memory management or parallel GC is that concurrent GCs create a performance penalty on every reads and writes Not on every read a

> The difference with manual memory management or parallel GC is that concurrent GCs create a performance penalty on every reads and writes Not on every read and write, but it could be on every load and store of a reference (i.e. reading a reference from the heap to a register or writing a reference from a register to the heap). But what difference does it make where exactly the cost is? What matters is how much CPU is spent on memory management (directly or indirectly) in total and how much latency memory management can add. You are right that the low-latency collectors do use up more CPU overall than a parallel STW collector, but so does manual memory management (unless you use arenas well).