[tsimionescu]

The point is that it's very hard to predict how much of an impact the GC will have a priori. You can of course measure after the fact, and try to improve, but it's hard to architect your system in a way that you can more or less guarantee will get good GC performance (other than just not allocating any memory, of course). Malloc actually suffers from a similar problem: it's just hard to know a priori if your access patterns will work well with the internals of your allocator/GC.

[p_l]

IBM Metronome and similar approaches provide very strong guarantees (if you keep a certain bound on garbage creation ofc) at the expense of throughput.

What they lose is that they introduce also a certain guaranteed loss of available cpu time, due to optimizing for latency and real-time predictability.

[neonsunset]

Respecting generational hypothesis is a good step towards engineering a GC-friendly design. Mind you, this brings back the necessity to reason about object lifetime, something a GC-based language absolves you from, but it does help. It tends to teach you a lesson that sometimes higher allocation count of objects that die in Gen 0 is preferable to fewer larger allocations which have higher chance of surviving until Gen 1 (.NET has three main generations for GC objects - 0 and 1 aka ephemeral and 2 aka long-lived, there are also LOH, POH and NonGC-heap).