some results in the README. Perl holds up well.
These are probably 10 years old though.
Tcl is historically very slow. Especially for synthetic CPU intensive benchmarks. However, since it's so easy to interop with C, it didn't seem to matter much in the real world. You just put anything performance sensitive in C and left the bits that didn't matter in tcl. Some benchmarks: https://github.com/trizen/language-benchmarks
Additionally, you can compile Tcl to machine code with TclQuadCode for up to a 66x speed improvement
It takes Little 3.53 seconds to find the 33rd number in the Fibonacci sequence recursively versus 30.23 seconds for Tcl8.6 on my i5-3320M.