Optimize ColumnGatherer

[SergeiPavlov]

Use SortedSet<> for most typical case instead of .Distinct().OrderBy() LINQ

[botinko]

It's not obvious, that it's faster on dotnet 10.

[SergeiPavlov]

It's not obvious, that it's faster on dotnet 10.

SortedSet<> constructor uses Array.Sort()

OrderBy() uses QuickSort() + .Distinct() uses HashSet
Such algorithms cannot be inlined and reduced. QuickSort is recursive by its nature

• SortedSet saves a few iterator allocations

[snaumenko-st]

But I think we should probably have a benchmark for each similar change. Otherwise it's not obvious whether it's worth optimizing or not.

[SergeiPavlov]

But I think we should probably have a benchmark for each similar change.

Benchmarking increases development time significantly.
That is why I prefer to make changes when the advantage is logically evident