Hello,
currently we are running Atlassian Confluence Server 8.1.0.
The mentioned problem occures when we want to edit a page.
The edit button is loading infinitly. Then confluence opens the page after 2 minutes or it shows a error message with " Site is not responding" following with two options:
"Do you want to wait or leave this page?"

Same problem occures if want to save the recently opened file.
What we've done without success:
#CATALINA_OPTS="-Xms1024m -Xmx1024m
->
#CATALINA_OPTS="-Xms2048m -Xmx2048m