One character at a time is still slow, as my benchmarks below showed. This solution still benchmarked at about 4 cps, and my buffered solution gave about 1100 cps.

Update: BTW, have you looked at File::Tail? It searches from the end of the file also, and if you don't want 'tail -f' behavior (i.e. a blocking read), then you can do:

my $fh = File::Tail->new(name=>$filename,tail=>$lines);
$fh->nowait(1);
print $line while $line=$line->read;
[download]

The performance is not horrible on large files, though a bit worse than my function, probably due to the overhead having all sorts of bells and whistles that are not being used.