Disconnecting very often - capacity of one server?


first of all, than you for the wonderfull community, I am new in the XMPP servers world and read all this post help me very much.

I am testing the number of concurrent connections that one server can support and I am doint it in a very small server from digitalocean.com with only 512MB of ram.

I already installed openfire and setup one web-client to test everything in a MUC room.

My first idea was open 15-20 tabs and connect with different usernames to the room, but my surprise is that if I open all this tabs from the same browser everything works veeeery slow and with disconnections (in this browser), however if concurrently in another browser I open a session everything works smooth.

I have two questions, anyone knows why opening several tabs +10 from a browser make unusable the chat in this browser? How much concurrent connections do you stimate I can have in the smallest server in digitalocean (512mb ram)?

Thanks in advance