perl-5.38.2
==========
           Rate    (?{})    chomp     =()=    while   rindex    index split_by
(?{})     216/s       --     -64%     -70%     -75%     -78%     -81%     -96%
chomp     599/s     177%       --     -17%     -31%     -40%     -47%     -90%
=()=      718/s     232%      20%       --     -18%     -28%     -36%     -88%
while     872/s     303%      46%      21%       --     -13%     -22%     -85%
rindex    999/s     362%      67%      39%      15%       --     -11%     -83%
index    1120/s     418%      87%      56%      28%      12%       --     -81%
split_by 5749/s    2559%     860%     701%     559%     475%     413%       --

perl-5.32.0
==========
           Rate    (?{})    chomp     =()=    while    index   rindex split_by
(?{})     228/s       --     -59%     -64%     -75%     -77%     -78%     -95%
chomp     555/s     143%       --     -12%     -39%     -44%     -47%     -89%
=()=      627/s     175%      13%       --     -31%     -37%     -41%     -88%
while     913/s     300%      65%      46%       --      -9%     -13%     -82%
index     999/s     338%      80%      59%       9%       --      -5%     -80%
rindex   1056/s     362%      90%      68%      16%       6%       --     -79%
split_by 5046/s    2110%     810%     705%     452%     405%     378%       --

perl-5.20.1
==========
           Rate     =()=    (?{})    chomp   rindex    index    while split_by
=()=      372/s       --     -19%     -22%     -54%     -54%     -56%     -96%
(?{})     462/s      24%       --      -3%     -43%     -43%     -45%     -95%
chomp     478/s      29%       4%       --     -41%     -41%     -43%     -95%
rindex    807/s     117%      75%      69%       --      -1%      -3%     -92%
index     814/s     119%      76%      70%       1%       --      -3%     -92%
while     836/s     125%      81%      75%       4%       3%       --     -91%
split_by 9752/s    2524%    2013%    1941%    1108%    1099%    1066%       --