The poster is using grep 2.5.3. Release notes for 2.6 talk about UTF-8 performance improvements: "This release fixes an unexpectedly large number of flaws, fr

The poster is using grep 2.5.3. Release notes for 2.6 talk about UTF-8 performance improvements: "This release fixes an unexpectedly large number of flaws, from outright bugs (surprisingly many, considering this is "grep") to some occasionally debilitating performance problems." Current version of grep is 2.10.