Clearly it isn't in the best interest of anyone to allow hostility to get out of control. A simple solution would be to have a mod come in and clean things up but this situation left me wondering how Stack Overflow itself could help diffuse hostility? Maybe you could look into implementing something similar to what Hacker News does by adding an ever increasing delay to posting comments as the number of comments increase.
This was a question about some very doubtful micro-optimization, and in the end there still is no clear use-case. The OP did throw in some totally unrelated (as it turned out) code, after many requests for clarification.
In the end, if I look over the comments (I guess I was in your "mob" as well), I see no unacceptable behaviour. Let alone hostile. Just a lot of good advice going unheeded, and an OP who is very insistent on doing the wrong thing, only reluctantly explaining the issue.
In the end, an SO "mob" just tried to rescue a very bad question.
If you find an case of out of control hostility then flag it for a moderator. I don't think comments should be delayed, this would hamper needed clarification/communication even in cases where there were several comments.
Stack Overflow has to contend with a problem that afflicts all helping communities: annoyance and repeated stupidity. Or at least repeated apparent stupidity.
This question is a fine example. The OP asked about a micro-optimization that would in the vast majority of cases be deeply pointless. He didn't include a use case, and he didn't indicate why he though this was an important thing to optimize.
In theory none of this is a problem. But many people who read that question said to themselves "Again?!?".
Stack Overflow sees a lot of these, and most of them are asked by relative newcomers who don't really know what they are doing, or what they should be doing to optimize. Telling them not to bother, and pointing them at the reason why is doing them a bigger service than answering the question.
A really experienced poster would know to say "I know this is usually stupid, but I think it is important in this case because...".
To be sure, the OP hasn't posted a bunch of these before, but I'd give dollar to donuts that the users responding in the comment thread have dealt with a bunch of them. A tendency toward curtness is natural, though it should obviously be held in check.
Here is a place where a gentle comment could help both to remind the commentariate to be nice and to smooth the posters ruffled feathers. If it goes beyond that stage, flag for a moderator.
To analyze this particular case
The initial comments were polite, but of the "Are you sure you want to do this?" variety.
The OP responded with "I'm going to process a lot of data.", but still with no suggestion of why this seemed like a good idea. (He may have thought "a lot of data" was a reason, but that doesn't help his case.)
After that the comments get more strongly worded, but there are still helpful in intent.
The OP eventual gets fed up enough to post
Frankly I find the OP's intransigence more troubling then the admittedly hot-n-heavy attempts to help the OP figure out if this was or was not a good idea. Scolding and berating people who are trying to help you is not a way to make friends.