I'd be very interested to see your results that show diffrently.

Cut, paste, copy Chatter.bat (33KB) to "file", run:

Benchmark: running BufferedFileHandle, chunk, linebyline, each for at 
+least 3 CPU seconds...
BufferedFileHandle:  4 wallclock secs ( 3.46 usr +  0.00 sys =  3.46 C
+PU) @ 386.13/s (n=1336)
     chunk:  4 wallclock secs ( 3.63 usr +  0.00 sys =  3.63 CPU) @ 31
+0.19/s (n=1126)
linebyline:  4 wallclock secs ( 3.40 usr +  0.00 sys =  3.40 CPU) @ 43
+4.71/s (n=1478)
[download]

This shows that default line-by-line is the fastest (434/s), enlarged buffer line-by-line is the 2nd fastest (386/s), and chunk and split is the slowest (310/s).

Now append Chatter.bat to "file" until we have a 1GB file. Now we have buffered@15/s, line-by-line@13/s, chuck@9/s.

Find 85MB file: buffered@0.20/s, line-by-line@0.19/s, chunk@0.12/s.

I'd personally consider perl broken if it couldn't read a line at a time faster than I could in Perl code. Previous benchmarks have shown that Perl's overriding of stdio buffers can make perl's I/O faster than I/O in C programs using stdio. So I must be missing something about (at least) your copy of perl to understand why standard line-by-line isn't faster.

Update: I removed a pointless sentence that was probably snide. I apologize to those who already read it.

        - tye (but my friends call me "Tye")