Major performance issue with file upload / Spring Web Flow

[JockeF]

We are developing a web-application in Spring Web Flow 2.3.1 with several states, where one of the states allows the user to upload one or more files to the server. The files themselves are used at a later state, so in the meantime we store the content of the files in byte arrays in flow scope.

The problem is that when uploading larger files (about 2mb) it gets really slow. Each request (any request to the server) takes 30s+.

Is this a known problem? Should we not store the file contents in flow scope?
Is there a better way to do this? e.g store the files in session instead?

Appreciate any advice on this, Thanks
Joakim