| Compiler | Operating System | Hardware | Number of includes used for test | Time for external include guard compile | Time for internal include guard compile | Time for no include guard compile | Include guard optimisation implemented? |
| Watcom C++ 11.0 (wpp386) |
Windows 98 | Pentium II 300 MHz | 10,000 | 0.27 s | 0.50 s | 7.69 s | YES |
| Watcom C 11.0 (wcc386) |
Windows 98 | Pentium II 300 MHz | 10,000 | 0.27 s | 10.88 s | 12.86 s | NO |
| Cygwin B20.1 EGCS (2.91.57) | NT 4.0, SP3 (using Cygwin B20.1 bash shell) | Pentium II 400 Mhz | 100,000 | 1.9 s | 1.5 s | 88.5 s | YES |
| Cygwin B20.1 EGCS (2.91.57) - running over networked drive | NT 4.0, SP3 (using Cygwin B20.1 bash shell) | Pentium II 400 Mhz | 100,000 | 10.9 s | 4.9 s | 450.9 s | YES |
| gcc version egcs-2.91.66 (egcs-1.1.2 release) | S.u.S.E. Linux 6.2 | Pentium II 300 MHz | 100,000 | 4 s | 3 s | 16 s | YES |
| gcc version 2.95.1 19990816 (release) | Debian GNU/Linux 2.1 | Dual Pentium II 400Mhz | 100,000 | 0.9 s | 0.6 s | 10.2 s | YES |
| SparcWorks SC4.2 | Solaris 2.6 | Ultra 2300, 2*300Mhz Ultra Sparc | 100,000 | 2.1 s | 19.2 s | 22.7 s | NO |
| SparcWorks SC5.0 | Solaris 2.6 | Ultra 2300, 2*300Mhz Ultra Sparc | 100,000 | 3.4 s | 23.5 s | 33.0 s | NO |
| Microsoft VC5 SP3 | NT4 SP5 | Dual Pentium II 450Mhz (Compaq AP500) | 10,000 | 0.2 s | 10.68 s | 11.2 s | NO |
| Microsoft VC5 SP3 using precompiled headers | NT4 SP5 | Dual Pentium II 450Mhz (Compaq AP500) | 10,000 | 0.2 s | 3.2 s | 3.1 s | Not applicable due to use of precompiled headers |
| Microsoft VC6 SP3 | NT4 SP5 | Dual Pentium II 450Mhz (Compaq AP500) | 10,000 | 0.2 s | 11.2 s | 11.7 s | NO |
| Microsoft VC6 SP3 using precompiled headers | NT4 SP5 | Dual Pentium II 450Mhz (Compaq AP500) | 10,000 | 0.2 s | 3.1 s | 3.2 s | Not applicable due to use of precompiled headers |
| Borland C++ Builder 3.0 (bcc32 v 5.3) | NT 4.0, sp 5 | Pentium II 350 Mhz | 10,000 | 0.36 s | 9.84 s | 10.92 s | NO |
| Borland C++ Builder 4 (bcc32 v 5.4) | NT 4.0, SP3 (using Cygwin B20.1 bash shell) | Pentium II 400 Mhz | 100,000 | 0.7 s | 1.5 s | 61.6 s | YES |
| Borland C++ Builder 4 (bcc32 v 5.4) - running over networked drive | NT 4.0, SP3 (using Cygwin B20.1 bash shell) | Pentium II 400 Mhz | 100,000 | 7.8 s | 2.6 s | 498.1 s | YES |
| Microsoft Visual Studio 2008 | Windows 7 | AMD Opteron 165 Dual Core 1.81 GHz | 50,000 | 0.13 s | 5.48 s | 5.77 s | NO |
| GCC 4.5.2 (mingw32) | Windows 7 64 bit | Intel Core i7 2600 3.4Ghz | 100,000 | 0.14 s | 0.11 s | 5.21 s | YES |
| GCC 4.2.1 | OpenBSD 5.0 | loongson laptop (800Mhz) | 10,000 | 0.14 s | 0.10 s | 0.79 s | YES |
| GCC 4.7.3 | Ubuntu 13.04/Linux 3.8 | Intel Core i5-2450M CPU @ 2.50GHz × 4 | 3,000,000 | 2.160 s | 1.263 s | 21.562 s | YES |
| Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21114 for x86 (Nov 2013 CTP) | Windows 7 64 bit | Intel Core 2 Quad CPU Q8400 @ 2.66 GHz | 1,000,000 | 0.59 s | 13.74 s | 75.24 s | NO (1) |
| GCC 4.8.2 | Cygwin 64 bit running on Windows 7 64 bit | Intel Core 2 Quad CPU Q8400 @ 2.66 GHz | 1,000,000 | 0.959 s | 0.811 s | 102.545 s | YES |
The only thing these timings should be used for is to assess whether a particular compiler has implemented the internal include guard optimisation.
Thank you to everyone who has submitted results. If you would like to submit results for a compiler not yet listed, please make sure you include all of the details mentioned in the table.