Fine that it now works for you.
Generally allocating heap objects in a narrow loop can make programs slow, that is not really a GC issue, but due to the many allocations. I read that some other languages like Java or Python cache allocations, but I think current Nim does not much caching for allocations. Note that while seqs and strings are stack objects in recent Nim, they have memory allocated on heap for storing content. Maybe soon you can use Nim's new Destructors.
