Performance and scability

Hi,

I've imported 40000 documents in repository with REST api.

For one text file, the import task time is min 10s.
Files length is 3ko max.

My configuration is : 
   nuxeo 5.1.5GA
   Mysql 5.0.27 for storage
   Linux 64bits 
   32gb memory ...

Is there some requirements for repository storage ?
Is there some articles about performance capabilities ?

Thx
Regards,
Pascal