> a let just to bind one local at the head of a function really bugged me, so I would use &aux to avoid it.
> Of course I try not to use LET (I think there is a tax on it)
In Cadence Skill, the lisplike we use in the office, 'let does have a tax to it when using lexical bindings; environments were pretty hefty objects and using 'let in a loop would generate a lot of them as garbage (the language implementation doesn't even have tail call opts!). I ended up using @optional (approximately equal to &optional) for some variables in time-constrained code, which helped reduce environments.
