No elegant alternative. As I showed in the benchmark, this works fine:

sub splt{split" ",reverse((split" ",(reverse$x),1)[0]),1;};
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The most elegant approach to this problem is the use of tr function. The implementation below beats regex three times and can be made faster by trivial extension of tr function mentioned in my prev post (something like option 'x' -- stop the translation on the first symbol outside the set1 and return this position), which can be used instead of more general function index for searching single characters in the string and can made like rindex to be able to search in reverse direction too.

Looks like the solution for trim from the Cookbook mentioned by Fletch along with potentially deforming the string is slower then regex in my test(on my machine it took 3.56 sec real time).

Here is the "tr based" algorithm for trim:

time perl -e 'for (1..1000000) { $line=" aaa bbb ccc ddd eee fff "; $_=$line; $_=~tr/ /x/c; $start=index($_,'x'); $line=substr($line,$start,rindex($_,'x')-$start+1); }'

real 0m1.112s
user 0m1.076s
sys 0m0.031s

Can be made into a single statement making it slightly( ~7%) slower:

$line=substr($line,($start=index($_=$line=~tr/ /x/cr,'x')),rindex($_,'x')-$start+1);

# time perl -e 'for (1..1000000) { $line=" aaa bbb ccc ddd eee fff "; $line=substr($line,($start=index($_=$line=~tr/ /x/cr,'x')),rindex($_,'x')-$start+1); }' 
real 0m1.189s
user 0m1.154s
sys 0m0.015s