What I'd appreciate is some independent confirmation that the two HTML output files look the same in Safari and some timing results from a different setup.
Below are some results. I've chopped off the first two calls from each because both osascript and tclsh have first-run overhead after a restart and it was unfair to osascript to consider it's longer first-run startup penalty. As anyone can probably verify, after the handicap, osascript consistently takes an order of magnitude greater amount of time to produce the same result.
[Desktop]# time osascript asisbn.scpt
real 0m0.410s
user 0m0.265s
sys 0m0.037s
[Desktop]# time osascript asisbn.scpt
real 0m0.403s
user 0m0.264s
sys 0m0.035s
[Desktop]# time osascript asisbn.scpt
real 0m0.406s
user 0m0.264s
sys 0m0.036s
[Desktop]# time osascript asisbn.scpt
real 0m0.406s
user 0m0.265s
sys 0m0.036s
[Desktop]# time osascript asisbn.scpt
real 0m0.406s
user 0m0.265s
sys 0m0.036s
[Desktop]# time osascript asisbn.scpt
real 0m0.405s
user 0m0.264s
sys 0m0.035s
[Desktop]# time tclsh tclisbn.tcl
real 0m0.031s
user 0m0.014s
sys 0m0.010s
[Desktop]# time tclsh tclisbn.tcl
real 0m0.030s
user 0m0.014s
sys 0m0.010s
[Desktop]# time tclsh tclisbn.tcl
real 0m0.029s
user 0m0.014s
sys 0m0.010s
[Desktop]# time tclsh tclisbn.tcl
real 0m0.029s
user 0m0.014s
sys 0m0.011s
[Desktop]# time tclsh tclisbn.tcl
real 0m0.029s
user 0m0.014s
sys 0m0.010s
[Desktop]# time tclsh tclisbn.tcl
real 0m0.029s
user 0m0.014s
sys 0m0.010s