[nicoburns]

I find that these kind of optimizations are usually more about technical architecture than leetcode. Last time I got speedups this crazy the biggest win was reducing the number of network/database calls. There were also optimisations around reducing allocations and pulling expensive work out of hot loops. But leetcode interview questions don't tend to cover any of that.

They tend to be about the implementation details of specific algorithms and data structures. Whereas the important skill in most real-world scenarios would be to understand the trade-offs between different algorithms and data structures so that you pick an appropriate off-the-shelf implementation to use.

[LollipopYakuza]

I agree. The "advanced" leetcode is about those last % of optimization. But when network latency is involved in a flow, it is usually the most obvious low hanging fruit.