CPU Usage Horror!

I use Fedora Core 3 where i installed the jivemessenger server and used smack as an interface for my users to jive but the problem is each time one user logs-on the cpu usage shot up from 5 to 50-70 and that is for one user only at an instance.

My horror now if multiple user will log on at the same time our linux box might fail all of its service (not really sure but the horror just thinking of it). So i tried to isolate the problem it seems to me that everytime smack logins to jive-messenger the jvm garbage collect like mad. I tried different options for the jvm but still get the same results. thus everytime the jvm will garbage collect the cpu usage shots up.

Is there anyone can help me on this to minimize the cpu usage.

Thank you in advance