[samesisa]

I increase the -Xmx JVM option value on /opt/zimbra/bin/zmmailboxdctl to 4096 MB. The default of mailboxd_java_heap_memory_percen value was 40%. Now is 68'5%. We have 6 GB RAM on our server.

Zimbra recommend against increasing the heap size to more than 30% of system memory.
Performance Tuning Guidelines for Large Deployments - Zimbra :: Wiki

I read this errors from firefox during error:
<!-- com.zimbra.common.soap.SoapFaultException: system failure: getDirectContext
ExceptionId:btpool0-29:1255085575095:14cec69e5fdd0327
Code:service.FAILURE
at com.zimbra.common.soap.SoapJSProtocol.soapFault(So apJSProtocol.java:65)
at com.zimbra.common.soap.SoapTransport.extractBodyEl ement(SoapTransport.java:245)
at com.zimbra.common.soap.SoapTransport.parseSoapResp onse(SoapTransport.java:221)
at com.zimbra.common.soap.SoapHttpTransport.invoke(So apHttpTransport.java:251)
at com.zimbra.common.soap.SoapTransport.invoke(SoapTr ansport.java:297)
at com.zimbra.cs.zclient.ZMailbox.invoke(ZMailbox.jav a:543)
at com.zimbra.cs.zclient.ZMailbox.invoke(ZMailbox.jav a:537)
at com.zimbra.cs.zclient.ZMailbox.authByPassword(ZMai lbox.java:482)
at com.zimbra.cs.zclient.ZMailbox.&lt;init&gt;(ZMailb ox.java:393)
at com.zimbra.cs.zclient.ZMailbox.getMailbox(ZMailbox .java:342)
at com.zimbra.cs.taglib.tag.LoginTag.doTag(LoginTag.j ava:122)
at org.apache.jsp.public_.login_jsp._jspService(login _jsp.java:259)
at org.apache.jasper.runtime.HttpJspBase.service(Http JspBase.java:93)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:373)
at org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:477)
at org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:371)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at com.zimbra.webClient.servlet.JspServlet.service(Js pServlet.java:50)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:362)
at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:716)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:406)
at org.mortbay.jetty.servlet.Dispatcher.forward(Dispa tcher.java:268)
at org.mortbay.jetty.servlet.Dispatcher.forward(Dispa tcher.java:126)
at org.mortbay.jetty.servlet.DefaultServlet.doGet(Def aultServlet.java:465)
at org.mortbay.jetty.servlet.DefaultServlet.doPost(De faultServlet.java:496)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:727)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1093)
at com.zimbra.webClient.filters.SetHeaderFilter.doFil ter(SetHeaderFilter.java:283)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1084)
at org.mortbay.servlet.UserAgentFilter.doFilter(UserA gentFilter.java:81)
at org.mortbay.servlet.GzipFilter.doFilter(GzipFilter .java:132)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1084)
at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:360)
at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:716)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:406)
at org.mortbay.jetty.handler.ContextHandlerCollection .handle(ContextHandlerCollection.java:211)
at org.mortbay.jetty.handler.HandlerCollection.handle (HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:139)
at org.mortbay.jetty.handler.rewrite.RewriteHandler.h andle(RewriteHandler.java:315)
at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:313)
at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:506)
at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:844)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:644)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:381)
at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:396)
at org.mortbay.thread.BoundedThreadPool$PoolThread.ru n(BoundedThreadPool.java:442)
-->