\documentclass[]{minimal}
\usepackage{expl3}
\usepackage{l3benchmark}
\ExplSyntaxOn
\prg_new_conditional:Npnn \new_tl_if_empty:n #1 { p , TF , T , F }
{
\if:w \scan_stop: \__kernel_tl_to_str:w { #1 } \scan_stop:
\prg_return_true:
\else:
\prg_return_false:
\fi:
}
\prg_new_conditional:Npnn \new_tl_if_empty:o #1 { p , TF , T , F }
{
\if:w \scan_stop: \__kernel_tl_to_str:w \exp_after:wN { #1 } \scan_stop:
\prg_return_true:
\else:
\prg_return_false: