options variables: features vs. overhead (curiosity)

[René J.V. Bertin]

Hi,

Out of pure curiosity: what's the overhead incurred by using options variables as simple boolean state variables that are probably set only once but possibly read many times, compared to native Tcl variables?

I'm thinking in terms of cumulative effect on iterative or recursive operations like portindex and dependency calculations. 

Same thing with `[tbool foo]` instead of `[info exists foo] && ${foo}`: is there a significant overhead in Tcl in moving (frequent) operations to a procedure?

Thanks,
R.