Might be a lot to ask, depending on the time needed to write a couple of lines - but I guess right now it's most helpful for the people that are already educated on v8 performance.
It's just that you could easily educate a broader audience (cough - like the author here) with a short write up. Some things are 'obvious' (GC pressure), some (everything about 'In hot code', some of the trace parameters) things are opaque and ~meaningless~.
"In hot code" means "in code that comprises a substantial part of your execution". Presumably if you run try-catch or eval in non-hot code, it still runs slow, but not slow enough to make your whole program slow.
I wondered too if they had more to say about the usefulness of some of the trace parameters. I am pretty sure they refer to what the profiler traces (and logs), but I don't know whether they got any usefulness out of them.
What I meant was: The whole 'in hot code' part of the slides didn't make sense to me, because it's something like a list of (unexplained) statements. I know what 'hot code' refers to, I just don't particularly like to accept things as facts without a minimum of explanation. Probably the author is dead on and I'm sure he knows a lot more about the technology than I do, but 'don't use X, use Y' or 'avoid Z' is something that should be qualified.
The idea "in hot code" slides try to express is very simple: if you have a JavaScript function that should run as fast as possible then don't do this and that. Going into details requires a lot of speaking/writing so it was not an option for a 40m talk. I would not say that knowing which constructs should be avoided is meaningless. Of course it's great to know WHY they should be avoided but that requires deeper understanding of VM internals.
Trace parameters are there to give actual nodejs/v8 users a chance to experiment, to trace their app and see what optimizing compiler does to their code.
Might be a lot to ask, depending on the time needed to write a couple of lines - but I guess right now it's most helpful for the people that are already educated on v8 performance.
It's just that you could easily educate a broader audience (cough - like the author here) with a short write up. Some things are 'obvious' (GC pressure), some (everything about 'In hot code', some of the trace parameters) things are opaque and ~meaningless~.