The French Wikipedia loads several seconds faster for me.
I suspect this is at least partly just an instance of selective observation. For some people, one site probably loads slightly faster than the other for whatever random routing reason. Those who see the French site load first aren't going to complain, but those who see the English site load first _will_ complain. Hence, you only hear one side of what's really a two-sided issue.
Or at least that's my guess.
It could also be something about the round-robin DNS:
root@xoom:~>host en.wikipedia.org en.wikipedia.org has address 207.142.131.247 en.wikipedia.org has address 207.142.131.248 en.wikipedia.org has address 207.142.131.235 en.wikipedia.org has address 207.142.131.236 en.wikipedia.org has address 207.142.131.245 en.wikipedia.org has address 207.142.131.246 root@xoom:~>host fr.wikipedia.org fr.wikipedia.org has address 207.142.131.246 fr.wikipedia.org has address 207.142.131.247 fr.wikipedia.org has address 207.142.131.248 fr.wikipedia.org has address 207.142.131.235 fr.wikipedia.org has address 207.142.131.236 fr.wikipedia.org has address 207.142.131.245
Some browsers will choose an IP at random, but others take the first in the list. Maybe it's just that .246 is faster than .247 and some people's DNS servers have the order cached that way so the same IP is always returned first.
-Bill Clark
I was not precise enough. This feeling was quite strong about 3 or 4 weeks ago (or more ? time goes so quickly :-)). This was a time where fr.wikipedia was nearly stuck every day around 7pm-9pm. When I say "stuck", I really mean """stuck""". At that time, I could go on editing en or meta, it was very slow, but was definitly faster than fr.
Shai told me that the configuration a few weeks ago was different from what it is right now. In any cases, this slowliness is not the case any more. But I personally have no idea of config changes, so had no idea it was different a while ago. I think that the one-side or two-sided issue is not really relevant.
If you ask me, each time I go to the www.wikimedia.org (now about a week old), it is horribly slow to load pages. To the point that in spite of my wish to work on this website, I have hardly done anything on it yet because I do not have the patience to wait 10 to 20 seconds for a page to load or save.
I know not what is the problem. I just loaded the main page. The source writes <!-- Served by isidore.wikimedia.org in 0.20 secs. -->
Still the page took exactly 21 seconds to load.
Why ????
This is not "cultural" effect, this is just what I see.