Rush is a language derived from Tcl and was presented at the Tcl workshop in 1993. Here is more information: http://number-none.com/blow/papers/rush_tcl94.pdf

The abstract of the paper says:

Rush is a new language that looks and feels much like Tcl [?]; we offer a compiler that executes scripts a hundred times faster than Tcl 7.x, allowing programs to run at speeds close to their C-language counterparts. Rush incorporates many features from Tcl and contains new features. From Tcl, Rush acquires its syntax,  everything is a string  model, set of core commands and datatypes, scoping rules, C callout facility, and support for popular libraries, including Tk and Tcl-DP.New features in Rush include pass-byreference, first class [closures] and production rules. A generalization of operator syntax allows users to code in either command-style or operator-style syntax; a converter program provides a translation between the two forms. We introduce the language as a set of changes to Tcl, with a focus on performance issues and discussion of new features.

Does anyone use this today (2005)??