It may be worse, the problem is that it loads too many info per tab. If you do it on multiple processes it will not get any better.

Multiprocess Firefox currently only uses one process for all tabs (plus a browser UI process). The tab process will be sandboxed, so users will get some of the security benefits of multiple tabs without the memory overhead of tab-per-process.

If you want to experiment with more than one tab process, you can tweak the about:config pref "dom.ipc.processCount".

Thank you for the informations, I'll experiment.