well... I didn't get very far...
The Turck MMcache was kindly put asside by my admin (he is realy trying to help me on otherside so i won't comlpain) as my server is not a dedicated one.
They have push the upload limit of PHP to 8mb as i request.
But that doesn't help. As my server is in the US and i'm in Israel my connection is sometime quit slowed. I'm thinking about a kind of timeout as the biggest the file is the greater chances to hang i can get.
He have tried to upload up to 6.7mb without problem as i'm stuck around 2.7 (sometimes nothing is my bandwidth is reduced by emukle or other progs).
While doing this occured several server freeze till they reduced back the PHP limit.
May be in the end tiki is not buikld to support large file upload and gallerie but rather small documents ?