2.6.40.3-0.fc15.i686 is a kernel. The 2.6.40.3-0.fc15.i686 has been tested via the Phoronix Test Suite in the configurations listed below.
mikey-render-bench - Tests on Fedora 15, Fedora release 15, Intel Core i7-2600K, GeForce GTX 560 Ti, ASUS P8P67 LE, Pentium III, Gallium 0.4 on softpipe, HP Company
mikey-openarena - Tests on Fedora 15, Intel Core i7-2600K, GeForce GTX 560 Ti, ASUS P8P67 LE, Intel T2400, Intel Mobile 945GM, Dell Latitude D620
mikey-render-bench - Tests on Fedora 15, Intel Core i7-2600K, GeForce GTX 560 Ti, ASUS P8P67 LE, Intel T2400, Intel Mobile 945GM, Dell Latitude D620
snow-faerie - Tests on Fedora 15, Intel T2400, Intel Mobile 945GM, Dell Latitude D620
el1352 - Tests on MandrivaLinux 2010.2, Fedora 15, AMD Athlon II X2 220, GeForce 210, eMachines EL1352, Intel Celeron 2.40GHz, Gallium 0.4 on ATI RV350
jovan-10155-10653-31695 - Tests on Fedora 15, Intel Celeron 2.40GHz, Gallium 0.4 on ATI RV350
jovan-531-2591-22086 - Tests on Fedora 15, Intel Celeron 2.40GHz, Gallium 0.4 on ATI RV350
super-pi 1M - Tests on Fedora 15, Intel Celeron 2.40GHz, Gallium 0.4 on ATI RV350
Ubuntu 11.04: i686 vs. i686 PAE vs. x86_64: At the end of 2009 I published benchmarks comparing Ubuntu's 32-bit, 32-bit PAE, and 64-bit Linux kernels. Those tests were carried out to show the performance impact of using 32-bit with PAE (Physical Address Extension) support, which on the plus side allows up to 64GB of system memory to be addressable from 32-bit machines, but is still significantly slower than a 64-bit kernel and user-space.