Creating tuples might be a bottleneck

[KristofferC]

Playing around with PProf.jl it seems we spend a lot of time creating tuples (If I read the output correctly, 20% of full time on summer benchmark):

Perhaps it could be optimized somehow.

[NHDaly]

(If I read the output correctly, 20% of full time on summer benchmark):

Yep! To clarify, that's 0.43% of total time spent actually executing that frame (exclusive), and 20% of total time spent executing this frame and any functions it calls (inclusive)

[KristofferC]

This is not so strange since extremely hot functions like iterate return a tuple and we currently never elide forming that.