The reason is reportedly that the pre-compiled binary for Windows uses PGO (profile guided optimization), which is usually not enabled under Linux. Sure, the fact that GCC does not generate as efficient codes as VC may also be a reason.[1]

Firefox also supports PGO in Linux. However, I failed at this (3.5.1). The profile-generating binary always segfaults.

Other people have encountered the same problem, even with the official PKGBUILD from Arch Linux. It is said to be a compiler problem.

Well, gave up. Maybe I’ll try it again some time later, with a more “stable” version of GCC probably.

[1] This statement only applies to the 32-bit platform. It seems GCC does a very good job on x86-64.

Profile-guided optimization is a relatively new feature. GCC began supporting it starting version 4.0; Microsoft VC 2005; and Intel C/C++/Fortran 9 (?).

A typical PGO-enabled building requires three steps:

(1) Build a profile-generating binary;
(2) Run the binary, which automatically collects useful data – branch probability, etc.
(3) Rebuild the program, using the data (“profile”) from Step 2.

With PGO, Internet Explorer reportedly gains an improvement of 8%, and Firefox 11% in JavaScript.

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