I can hear "glxgears is not a benchmark" already \^_^/
Kultex did a comparison between slitaz,crunchbang,ubuntu showing the problem in the original slitaz-3.0 release thread from march 2010.
You want normal FPS on intel graphics boot into another distro ;)

Just for interest sake, but please type tazpkg search mesa and paste it here. I want to see which opengl packages you got installed.

Here is that thread mojo mentioned: http://forum.slitaz.org/index.php/discussion/comment/6272/#Comment_6272

Seems SliTaz defaults to software rendering instead of using the hardware.

First thank you 2 for answers.

@mojo : "You want normal FPS on intel graphics boot into another distro ;)"
What I want is normal FPS in SliTaz. It's not urgent, I don't need it. I just want to (try to) fix this... When I find an issue in a soft, and when I want to contribute and improve it, I don't search another soft, I search a solution.
I'm sure your perfectly understand this, because you are not stuck in W$ or Ubuntu, you are a SliTaz contributor :)

@Trixar_za : Thank you for the link. Here's the tazpkg search mesa result :

Search result for : mesa

Installed packages
================================================================================
mesa 7.8.1 x-window
mesa-demos 7.8.1 development
mesa-dri 7.8.1 x-window
mesa-dri-intel 7.8.1 x-window
================================================================================
4 installed package(s) found for : mesa

Available packages name-version
================================================================================
libegl-mesa-7.8.1
libglu-mesa-7.8.1
libglw-mesa-7.8.1
mesa-7.8.1
mesa-demos-7.8.1
mesa-dev-7.8.1
mesa-dri-7.8.1
mesa-dri-ati-7.8.1
mesa-dri-intel-7.8.1
mesa-dri-mga-7.8.1
mesa-dri-savage-7.8.1
mesa-dri-sis-7.8.1
mesa-dri-tdfx-7.8.1
mesa-dri-unichrome-7.8.1
================================================================================
14 available package(s) found for : mesa

I don't know what are the 3 first lib, maybe the solution is there? Or maybe some compilation option must be modified ?

xorg.conf module section :

Section "Module"
	Load  "dri"
	Load  "dbe"
	Load  "glx"
	Load  "dri2"
	Load  "extmod"
EndSection

Xorg.conf device section - maybe the problem is here :

Section "Device"
        ### Available Driver options are:-
        ### Values: : integer, : float, : "True"/"False",
        ### : "String", : " Hz/kHz/MHz"
        ### [arg]: arg optional
        #Option     "NoAccel"            	# []
        #Option     "SWcursor"           	# []
        #Option     "ColorKey"           	# 
        #Option     "CacheLines"         	# 
        #Option     "Dac6Bit"            	# []
        #Option     "DRI"                	# []
        #Option     "NoDDC"              	# []
        #Option     "ShowCache"          	# []
        #Option     "XvMCSurfaces"       	# 
        #Option     "PageFlip"           	# []
	Identifier  "Card0"
	Driver      "intel"
	VendorName  "Unknown Vendor"
	BoardName   "Unknown Board"
	BusID       "PCI:0:2:0"
EndSection

Nothing relevant in /var/log/Xorg.0.log : all module are loaded correctly, AIGLX and DRI2 enabled, no error, no warning except some missing fonts..

Here's how I configure my intel driver, before starting X :

tazpkg get-install xorg-xf86-video-intel
rm /dev/dri
mkdir /dev/dri
modprobe i915 modeset=1
modprobe drm
tazx config-xorg

Maybe a problem here :

tux@slitaz:~$ LIBGL_DEBUG="verbose" glxinfo
name of display: :0.0
libGL: OpenDriver: trying /usr/lib/dri/i915_dri.so
libGL error: failed to open drm device: Permission denied
libGL: OpenDriver: trying /usr/lib/dri/swrast_dri.so
display: :0  screen: 0
direct rendering: Yes

I'm having a similar issue with OpenGL at the moment. Previous SliTaz 3 ran glxgears, but now it doesn't work at all. Probably a lib I installed somewhere that made it work.

Anyway, from what I can see with the benchmark they did is that all the rendering ended up being done by the software and doesn't use the hardware at all. This might explain why OpenGL rendering is so slow because your CPU is doing all the work, while your graphic hardware just sits there not even being used by mesa.

The last ouput put me on the right way. While searching info about the permission problem I find someone saying "Why can root render with the proper drivers and user not?" on this page : https://bugs.launchpad.net/ubuntu/+source/linux/+bug/404064

This is a good question because :

tux@slitaz:~$ LIBGL_DEBUG="verbose" glxinfo | grep render
libGL: OpenDriver: trying /usr/lib/dri/i915_dri.so
libGL error: failed to open drm device: Permission denied
libGL: OpenDriver: trying /usr/lib/dri/swrast_dri.so
direct rendering: Yes
OpenGL renderer string: Software Rasterizer
    GL_NV_conditional_render, GL_NV_depth_clamp, GL_NV_fragment_program, 

root@slitaz:~# LIBGL_DEBUG="verbose" glxinfo | grep render
libGL: OpenDriver: trying /usr/lib/dri/i915_dri.so
libGL: Can't open configuration file /etc/drirc: No such file or directory.
libGL: Can't open configuration file /root/.drirc: No such file or directory.
direct rendering: Yes
OpenGL renderer string: Mesa DRI Intel(R) IGD GEM 20100328 2010Q1 x86/MMX/SSE2

root@slitaz:~# glxgears
Running synchronized to the vertical refresh.  The framerate should be
approximately 1/1936613746 the monitor refresh rate.
300 frames in 5.0 seconds = 59.951 FPS
301 frames in 5.0 seconds = 60.002 FPS
300 frames in 5.0 seconds = 60.000 FPS
301 frames in 5.0 seconds = 60.002 FPS

Only 60FPS because there's vertical sync, but in fact all run well with root user I can play eduke without problems (with tux even the menu is unusable ^^). I guess I must do something like add tux in video group or set DRI in 066 mode. I will find the solution and update tazx in consequence.

That works. Here's how I configure my intel driver now :

tazpkg get-install xorg-xf86-video-intel
rm /dev/dri
mkdir /dev/dri
tazx config-xorg
echo 'Section "DRI"
        Mode         0666
EndSection' > /etc/X11/xorg.conf.d/90-DRI.conf
modprobe i915 modeset=1
modprobe drm

I guess that adding a video group and add tux to it produce the same effect :

addgroup video
addgroup tux video

In fact this second solution was in the Xorg guide, but I missed it.
Using the DRI.conf seems to be an easier solution because some people doesn't use tux user. In the other hand, it's less secure because all user can access drm device.