Thank you Sherman for your reply. Decreasing MaxPermSIze seems to only make things worse , html previews gets slower, menu it's slower, and exports in general seems to be slower. That's the reason why I set MaxPermSize to 512m. I haven't check if the JVM consume the whole 2G ( In fact I don't really know how to) but it seems that it definetly takes a lot of memory on large exports, small, medium size reports seems ok. Is there any way, to optimize JasperServer or the report itself to make it faster for large reports exports?(Excel Reports, Pdf seems to work ok). -I already tried to make fields in the reports with the smallest posible height (so it decrease the number of pages) - Set Xmx Xmx PermSize MaxPerm size to several convinations... Is it normal that I can export large Reports to PDF but not to xls ,cvs or excel like files? Thanks in advance