Thank you for your inquiry.
Could you please specify which version of the GroupDocs.Viewer for Java library you use. Also will be useful if you share with us your file examples, with which occur the issue and your OS configuration (Java version, OS version, type of the project that you use ) .
Note: you can also try to increase Java heap size (for example -Xms1024m -Xmx1024m)
We will wait for your details.
Your Document Collaboration APIs
Follow us on LinkedIn, Twitter, Facebook and Google+