Anyway, this could be a legit complaint at this point.
I explained why that happens in my comment to the original post.
1) one with Buffers is also causing mark-sweep/compact pauses (7-15ms each) because Buffer constructor calls AdjustAmountOfExternalAllocatedMemory which triggers full gc cycle if it thinks that too much memory is held outside V8.
2) GCs in string based benchmark are mainly scavenges taking 0 ms plus < 10 full collections taking <6ms each on my desktop.
That is all I can say. V8 GC is performing well here from my point of view.
Updating your post sounds like a nice idea. It created a lot of confusion among developers.
Strictly speaking I am not even convinced that GC is bottleneck here. Only profiling can reveal the real bottleneck.
[I tried small experiment: used thirdparty pure-JS JSON parser instead of V8 JSON.parse --- that changed GC profile, but did not affect response time.]