I have just took a quick glimpse and the source seems to be written very clearly. It is an excellent example of how coding in tcl looks like. Perhaps this could be used as an example when you are learning to program in tcl.

I don't use tcl neither I know what the actual state of available libraries the performance is, but tcl honors its fame as an easy to read language, this is not Perl.

One feature I like a lot is the ability to create secure interpreters that bypass military specifications.

Perhaps some benchmarks could give us an idea of what is the current state of affairs in the tcl world, but sometimes the bottle neck code just recurs to calling C libraries. I didn't see that ffi calling here.